阅读说明：本技术 一种大功率InGaAs/InP单行载流子光电探测器的设计方法 (Design method of high-power InGaAs/InP single-row carrier photoelectric detector ) 是由 龚世杰 郑谢恩 金运姜 于 2020-12-02 设计创作，主要内容包括：本发明公开了一种大功率InGaAs/InP单行载流子光电探测器的设计方法,包括以下步骤：S1：构建基于光吸收层、收集层、阻挡层单行载流子光电探测器；S2：分别构建光吸收层和收集层之间的异质结、阻挡层和光吸收层之间的异质结,给单行载流子光电探测器施加反向偏置电压；S3：根据反向偏置电压的分压结果,增加阻挡层的掺杂浓度提高单行载流子光电探测器饱和电流输出值。本发明通过对光电探测器阻挡层优化,改变阻挡层材料的掺杂浓度,提高了光电探测器饱和输出电流。(The invention discloses a design method of a high-power InGaAs/InP single-row carrier photoelectric detector, which comprises the following steps: s1: constructing a single-row carrier photoelectric detector based on a light absorption layer, a collection layer and a barrier layer; s2: constructing a heterojunction between the light absorption layer and the collection layer and a heterojunction between the barrier layer and the light absorption layer respectively, and applying a reverse bias voltage to the single-row carrier photoelectric detector; s3: and according to the voltage division result of the reverse bias voltage, increasing the doping concentration of the barrier layer and improving the saturation current output value of the single-row carrier photoelectric detector. According to the invention, the doping concentration of the barrier layer material is changed by optimizing the barrier layer of the photoelectric detector, so that the saturation output current of the photoelectric detector is improved.)

1. A design method of a high-power InGaAs/InP single-row carrier photodetector is characterized by comprising the following steps:

s1: constructing a single-row carrier photoelectric detector based on a light absorption layer, a collection layer and a barrier layer;

s2: constructing a heterojunction between the light absorption layer and the collection layer and a heterojunction between the barrier layer and the light absorption layer respectively, and applying a reverse bias voltage to the single-row carrier photoelectric detector;

s3: and according to the voltage division result of the reverse bias voltage, increasing the doping concentration of the barrier layer and improving the saturation current output value of the single-row carrier photoelectric detector.

2. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 1, wherein said light absorption layer is a P-type heavily doped InGaAs light absorption layer.

3. A method as claimed in claim 1, wherein the collection layer is a lightly N-type doped wide band gap InP collection layer.

4. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 1, wherein said blocking layer is a wide band gap heavily doped P-type InGaAsP blocking layer.

5. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 4, wherein said light absorbing layer and said collection layer are spatially separated, said light absorbing layer and collection layer have different concentration, electrons/holes will diffuse towards both ends of the collection layer simultaneously, and carrier electrons are blocked by the P-type InGaAsP barrier layer near the anode and diffuse only towards the collection layer, so as to form single-row carriers.

6. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 1, wherein the saturation output current of the single-row carrier photodetector can be increased by increasing the doping concentration of the blocking layer.

7. The apparatus as claimed in claim 1, wherein the photodetector is a high power InGaAs/InP single-row carrier photodetectorThe method is characterized in that the barrier layer has a forbidden band width of E_g1.35eV InP.

8. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed In claim 1, wherein said barrier layer is In with gap width of 1.1eV_0.82Ga_0.18As_0.4P_0.6。

9. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 7, wherein the doping concentration of InP is 1.2x10¹⁸cm^-3—3x10¹⁸cm^-3。

10. The design method of a high power InGaAs/InP single-row carrier photodetector as claimed in claim 1, wherein said reverse bias voltage is in the range of 0-10V.

Technical Field

The invention relates to the technical field of photoelectricity, in particular to a design method of a high-power InGaAs/InP single-row carrier photoelectric detector.

Background

The ability of photodetectors to convert incident optical signals into electrical signals is one of the key components of fiber optic communication systems. The future communication technology is developed towards high speed and large capacity, the requirements on the performance of the photoelectric detector are continuously increased, and the detector is required to have high-speed response and sufficient output optical power. The traditional PIN photodetector has the problem of mutual restriction between bandwidth and quantum efficiency, and can generate a strong space charge effect under the condition of high light intensity injection so as to limit the output of saturated photocurrent, so that the requirement of a future communication system on a receiving-end photodetector is difficult to meet. Although the avalanche photodiode has a large output gain and requires a large operating voltage, when the incident light power is large, noise due to the gain is large and current distortion is large. Although the optical waveguide photodetector can solve the mutual restriction between the bandwidth and the quantum efficiency, incident light is rapidly absorbed and saturated by the absorption layer on the front end waveguide layer, and the distribution of photocurrent is not uniform, thereby affecting the overall output power.

The single-row carrier detector (UTC-PD) only uses electrons with higher speed as active carriers, so that the negative influence caused by hole carriers with lower drift speed is avoided, the space charge effect is inhibited, the bandwidth and saturation current of the detector can be obviously improved, and the high-power output of a device is facilitated. Therefore, when the UTC-PD is used as the photoelectric conversion device in the microwave photonic link (fig. 1), a part of amplification links can be omitted to directly output a high-power radio-frequency signal, so that the cost can be greatly saved and application scenarios can be increased.

The UTC-PD device includes an upper contact layer, a barrier layer, a transition layer, an absorption layer, a cliff layer, a collection layer, a lower contact layer, etc. (shown in fig. 2), and is usually subjected to one-time epitaxy by using a Metal Organic Chemical Vapor Deposition (MOCVD). The composition and doping of each layer of the UTC-PD have important influence on the performance of the single-row carrier photoelectric detector, and the single-row carrier photoelectric detector with high performance can be obtained by designing and optimizing each epitaxial structure (comprising an absorption layer, a barrier layer, a cliff layer, a collection layer and the like) of the single-row carrier photoelectric detector. Most of the current designs are directed to absorption layers, cliff layers, collection layers, etc. (j.w.shi, j. -w.shi, expression high utilization current base width product performance of a near base ceramic with a flip-chip bonding structure, IEEE of Journal of Quantum electronics,2010,46(1):80-86), and there are few designs and optimizations directed to device barrier layers.

Disclosure of Invention

The invention provides a design method of a high-power InGaAs/InP single-row carrier photoelectric detector, aiming at overcoming the defect that the saturation output power is improved by optimizing a photoelectric detector barrier layer in the prior art.

The primary objective of the present invention is to solve the above technical problems, and the technical solution of the present invention is as follows:

a design method of a high-power InGaAs/InP single-row carrier photodetector comprises the following steps:

s1: constructing a single-row carrier photoelectric detector based on a light absorption layer, a collection layer and a barrier layer;

s2: constructing a heterojunction between the light absorption layer and the collection layer and a heterojunction between the barrier layer and the light absorption layer respectively, and applying a reverse bias voltage to the single-row carrier photoelectric detector;

s3: and according to the voltage division result of the reverse bias voltage, increasing the doping concentration of the barrier layer and improving the saturation current output value of the single-row carrier photoelectric detector.

Further, the light absorption layer is a P-type heavily doped InGaAs light absorption layer.

Further, the collecting layer is an N-type lightly doped wide band gap InP collecting layer.

Further, the barrier layer is a wide-band-gap P-type InGaAsP heavily-doped barrier layer.

Furthermore, the light absorption layer and the collection layer are in a spatially separated structure, concentration difference exists between the light absorption layer and the collection layer, electrons/holes can be diffused to two ends of the collection layer at the same time, carrier electrons are blocked by the barrier layer of the P-type InGaAsP close to the anode and are diffused to the collection layer only, and a single-row carrier is formed.

Further, the saturation output current of the single-row carrier photodetector can be increased by increasing the doping concentration of the blocking layer.

Further, the barrier layer has a forbidden band width of E_g1.35eV InP.

Further, the barrier layer is In with the forbidden band width of Eg 1.1eV_0.82Ga_0.18As_0.4P_0.6。

Further, the doping concentration of InP is 1.2 × 10¹⁸cm^-3—3x10¹⁸cm^-3。

Further, the reverse bias voltage range is 0-10V.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

according to the invention, the doping concentration of the barrier layer material is changed by optimizing the barrier layer of the photoelectric detector, so that the saturation output current of the photoelectric detector is improved.

Drawings

Fig. 1 is a schematic diagram of a UTC-PD based microwave photonic link.

Fig. 2 is a schematic view of an epitaxial structure of the high-power single-carrier photodetector of the present invention.

FIG. 3 is a flow chart of the method of the present invention.

FIG. 4 shows the barrier layers InP and In, respectively_0.82Ga_0.18As_0.4P_0.6The electric field intensity of the barrier layer and the cliff layer is shown schematically.

FIG. 5 shows the barrier layer of InP with a doping concentration of 1.2X10¹⁸cm^-3To 3x10¹⁸cm^-3Electric field intensity of the barrier layer and cliff layer is shown schematically.

FIG. 6 shows the barrier layer being In_0.82Ga_0.18As_0.4P_0.6Doping concentration of 1.2x10¹⁸cm^-3Schematic 3db bandwidth of the photodetector.

Fig. 7 is a graph showing the variation of output photocurrent with incident light power when different materials and doping concentrations are used for the blocking layer.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

Example 1

As shown in fig. 3, a design method of a high-power InGaAs/InP single-row carrier photodetector includes the following steps:

s1: constructing a single-row carrier photoelectric detector based on a light absorption layer, a collection layer and a barrier layer;

s2: constructing a heterojunction between the light absorption layer and the collection layer and a heterojunction between the barrier layer and the light absorption layer respectively, and applying a reverse bias voltage to the single-row carrier photoelectric detector;

s3: and according to the voltage division result of the reverse bias voltage, increasing the doping concentration of the barrier layer and improving the saturation current output value of the single-row carrier photoelectric detector.

In a specific embodiment, when a reverse bias voltage is applied to the single-row carrier photodetector, the applied reverse bias voltage is largely divided across the heterojunction.

It should be noted that before the photodetector enters the saturation state, the output current linearly increases with the increase of the incident light power, but when the incident light power is too high, the output current approaches saturation, and the main reason for the saturation is that with the increase of the light power, carriers in the photodetector will be accumulated in the absorption layer to induce a space charge shielding effect, that is, an electric field opposite to the self-established electric field and the reverse bias voltage of the photodetector is generated, so that the self-established electric field is slowly weakened until the self-established electric field collapses, the drift speed of the carriers is reduced, and the high saturation output characteristic of the photodetector is further deteriorated. The following methods may be used to improve the performance of the photodetector, including: a light absorbing layer with gaussian doping, a counter doping in the collection layer and the introduction of a heavily doped cliff layer. The existence of the cliff layer enables the electric field intensity at the heterojunction interface formed by the light absorption layer and the collection layer to be increased, and the electric field intensity is beneficial to electrons to pass through a potential barrier at the heterojunction, so that the accumulation of the electrons at the position is reduced, the accumulation of the electrons at the light absorption layer is further reduced, and the saturation current of the photoelectric detector is increased. Meanwhile, the cliff layer extends the electric field to the light absorption layer, so that the movement mode of the electrons is converted from diffusion movement to drift movement and diffusion movement, the accumulation degree of the transit time of the electrons in the light absorption layer is reduced, and the bandwidth and the saturation current of the photoelectric detector are increased.

In step S3, the electric field collapse caused by the space charge effect can be compensated by applying the reverse bias voltage, but in the case of large injection, the applied reverse bias voltage is mostly applied to the high electric field at the heterojunction, so that the applied bias voltage is more applied to the cliff layer by reducing the high electric field at the heterojunction of the blocking layer and the light absorption layer, which is beneficial to alleviating the space charge effect and increasing the saturation output current.

The reverse bias voltage can be in a range of 0-10V, and in a specific embodiment, 3V reverse bias voltage can be applied to the photoelectric detector, so that the larger the electric field of the barrier layer is, the smaller the electric field of the cliff layer is, which is not beneficial to electrons to rapidly pass through the light absorption layer, and the saturation current is limited, so that the electric field intensity of the cliff layer is enhanced by reducing the electric field intensity of the barrier layer, and the saturation current can be increased.

In a specific embodiment, the light absorption layer is a P-type heavily doped InGaAs light absorption layer, the collection layer is an N-type lightly doped wide bandgap InP collection layer, and the blocking layer is a wide bandgap P-type heavily doped InGaAsP blocking layer, wherein the light absorption layer and the collection layer are spatially separated, the light absorption layer and the collection layer have a concentration difference, electrons/holes are diffused to both ends of the collection layer at the same time, and carrier electrons are blocked by the P-type InGaAsP blocking layer near the anode and are diffused only to the collection layer, so that a single-row of carriers is formed. The blocking is effected by a conduction discontinuity at the heterojunction interface between the wide bandgap heavily doped barrier layer of P-type InGaAsP and the light absorbing layer of InGaAs.

It should be noted that the lightly doped concentration range is generally: 10¹⁵-10¹⁶cm^-3，The heavily doped concentration range is generally: 10¹⁷-10¹⁹cm^-3。

Further, the saturation output current of the single-row carrier photodetector can be increased by increasing the doping concentration of the blocking layer.

It should be noted that the reason why the saturation output current of the single-row carrier photodetector can be increased by increasing the doping concentration of the blocking layer is that when the blocking layer is made of a wide band gap material, a heterojunction formed by the wide band gap material is an abrupt homotype heterojunction, and the barrier width of the wide band gap material decreases as the doping concentration of the potential barrier wide band gap material increases.

d₂Barrier width, N, of wide band gap material_D2Is the doping concentration of the wide band gap material.

In a specific embodiment, the barrier layer may have a forbidden band width of E_gInP of 1.35eV or In of 1.1eV In band gap_0.82Ga_0.18As_0.4P_0.6The saturation output current can be increased.

In addition, InP having a larger forbidden band width is replaced with In having a smaller forbidden band width_0.82Ga_0.18As_0.4P_0.6The reason for (2) is: the material with wide band gap has large forbidden bandwidth and large resistivity, so the resistance is large, the divided reverse bias voltage is larger, and the cliff layer is not favorable for obtaining larger voltage. From the fermi level, electrons in the heterojunction can flow from a place with a high fermi level to a place with a low fermi level, so that materials with forbidden bandwidths can be exhausted, materials with narrow forbidden bands can accumulate electrons, the larger the difference between the fermi levels of the two materials is, the larger the exhausted region is, the larger the equivalent resistance is, the larger the divided reverse bias voltage is, and the larger voltage can be obtained by the cliff layer.

In a specific embodiment, the doping concentration range of the InP is 1.2 × 10¹⁸cm^-3—3x10¹⁸cm^-3Wherein the doping concentration is 1.2x10¹⁸cm^-3In the case of InP as the blocking layer, the saturation output current of the photodetector is 180mA, if the doping concentration is raised to 2x10¹⁸cm^-3The saturation output current can be increased to 209mA, and when the doping concentration is increased to 3x10¹⁸cm^-3The saturated output current may be increased to 229 mA. When the barrier layer is replaced with In_0.82Ga_0.18As_0.4P_0.6At this time, the saturation output current of the photodetector increased to 279 mA.

The following analysis was performed in combination with specific experimental data

FIG. 2 is a schematic view of an epitaxial structure of a high-power single-carrier photodetector of the present invention, In is used as a blocking layer_0.82Ga_0.18As_0.4P_0.6Doping concentration of 1.2x10¹⁸cm^-3. The light absorption layer is doped with Gaussian and has a peak concentration Nmax of 1.2x10¹⁸cm^-3Position of peak concentration X_dLocated at the top of the absorbent layer, the characteristic length L was 0.24. The thickness of the absorption layer is 1.1 μm, the applied bias voltage is-3V, the band gap gradient of the components is introduced to smooth the band gap between InGaAs and InP, and the cliff layer is introduced to increase the electric field at the heterojunction to moderate the space charge effect.

FIG. 4 shows illumination at 5 × 10⁴W/cm^-2And 7x10⁴W/cm^-2Temporal InP and In_0.82Ga_0.18As_0.4P_0.6When the materials are respectively used as barrier layer materials, the electric field intensity is compared with the graph, and In can be seen_0.82Ga_0.18As_0.4P_0.6When the material is used as a barrier layer, the barrier width of the barrier layer is narrower, the electric field intensity is smaller, more voltage can be applied to the cliff layer, and therefore the collection of electrons is promoted, and the saturation current is increased. When the light input is 7x10⁴W/cm^-2This result is more evident when InP is used as the blocking layer, and the electric field of the cliff layer is collapsed to show the saturation effect, but In_0.82Ga_0.18As_0.4P_0.6The cliff layer of the structure still has an electric field, and it can be concluded that In is used_0.82Ga_0.18As_0.4P_0.6The current saturation characteristics of the device can be obviously improved by respectively using the materials as the barrier layers.

FIG. 5 shows the concentration of InP barrier layerAre respectively 1.2x10¹⁸cm^-3、2x10¹⁸cm^-3、3x10¹⁸cm^-3The electric field intensity of the barrier layer and the cliff layer is increased, and it can be seen that the voltage divided by the barrier layer is reduced along with the increase of the doping concentration, and the electric field intensity of the cliff layer is improved. And the improvement of the electric field of the cliff layer is beneficial to relieving the space charge effect so as to obtain larger saturated output current.

Fig. 6 is the 3db response bandwidth of the photodetector of the structure of fig. 3, and it can be seen that at-3 db, the response bandwidth of the device is close to 24GHz, which meets the requirement of greater than 10GHz at design.

FIG. 7 shows the relationship between the output photocurrent and incident light power when different materials and doping concentrations are used for the barrier layer, and the increased doping concentration and In can be obtained_0.82Ga_0.18As_0.4P_0.6The use of InP as a barrier layer increases the saturation output current of the device, consistent with previous field strength analysis results, where the barrier layer is In_0.82Ga_0.18As_0.4P_0.6Doping concentration of 1.2x10¹⁸cm^-3The saturation output current is maximum and can reach 279 mA.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.