阅读说明：本技术 一种氦离子注入提升硅基探测器红外响应的方法 (Method for improving infrared response of silicon-based detector by helium ion implantation ) 是由 胡小龙 王昭 张子彧 邹锴 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种氦离子注入提升硅基探测器红外响应的方法,所述方法包括：将氦离子注入硅材料中产生缺陷态,当入射到硅基光电探测器上的光功率发生改变时,缺陷态吸收效应与表面态吸收效应同时作用会导致硅基光电探测器的光敏区域的导纳发生变化,实现硅基光电探测器对红外波段光功率的监测；所述硅基光电探测器为基于表面态吸收原理的垂直耦合透明光电探测器,包括：光敏探测器和信号读出电路。本发明利用氦离子注入在硅基光电探测器中引起缺陷态吸收,可以提升传统硅基光电探测器的红外响应,并且无需较大改动外围读出电路与封装方式。(The invention discloses a method for improving the infrared response of a silicon-based detector by helium ion implantation, which comprises the following steps: helium ions are implanted into a silicon material to generate a defect state, when the optical power incident on the silicon-based photoelectric detector changes, the admittance of a photosensitive area of the silicon-based photoelectric detector changes under the simultaneous action of the defect state absorption effect and the surface state absorption effect, and the monitoring of the silicon-based photoelectric detector on the optical power of an infrared waveband is realized; the silicon-based photoelectric detector is a vertical coupling transparent photoelectric detector based on the surface state absorption principle, and comprises: photosensitive detector and signal readout circuit. The invention utilizes helium ion implantation to cause defect state absorption in the silicon-based photoelectric detector, can improve the infrared response of the traditional silicon-based photoelectric detector, and does not need to greatly change a peripheral reading circuit and a packaging mode.)

1. A method for improving the infrared response of a silicon-based detector by helium ion implantation is characterized by comprising the following steps:

helium ions are implanted into a silicon material to generate a defect state, when the optical power incident on the silicon-based photoelectric detector changes, the admittance of a photosensitive area of the silicon-based photoelectric detector changes under the simultaneous action of the defect state absorption effect and the surface state absorption effect, and the monitoring of the silicon-based photoelectric detector on the optical power of an infrared waveband is realized;

the silicon-based photoelectric detector is a vertical coupling transparent photoelectric detector based on the surface state absorption principle, and comprises: photosensitive detector and signal readout circuit.

2. The method as claimed in claim 1, wherein the photosensitive detector comprises a photosensitive surface, an oxide layer, a gold electrode, and a substrate, and the sub-bandgap absorption is used to change the admittance of the device when the optical signal to be measured is incident on the photosensitive surface.

3. The method of claim 1, wherein the helium ion implantation is performed using a helium ion microscope,

the implantation was performed in a scanning manner using an accelerating voltage of 30kV, each implantation being for 0.25X 0.25nm²Until the entire target implant area is traversed.

4. The method of claim 1, wherein the signal readout circuit uses device admittance as readout signal,

the signal reading circuit consists of a trans-impedance amplifier and a phase-locked amplifier, the phase-locked amplifier provides alternating current driving voltage, a current signal is amplified by the trans-impedance amplifier and then input to a receiving end of the phase-locked amplifier for signal processing, and admittance change of a device is measured;

and calculating the optical power detected by the device according to the calibrated relation curve of the optical power and the admittance change.

5. The method of claim 1, wherein the method further comprises:

after helium ions are injected into the silicon-based photoelectric detector, the relation between the device admittance and the working frequency of a driving voltage source under different optical powers is obtained through testing, and the frequency with the most obvious admittance change is found as a working point;

after the working frequency is determined, the relation between the optical power and the admittance change under different wavelengths is calibrated again.

Technical Field

The invention relates to the field of optoelectronic devices, in particular to a method for improving infrared response of a silicon-based detector by helium ion implantation.

Background

The photoelectric detector is a basic device in the field of photoelectron, mainly functions to convert optical signals into electric signals, and is widely applied to the fields of communication interconnection, sensing imaging and the like. The silicon-based photoelectric detector is one of photoelectric detectors, and silicon is used as a main manufacturing material. The traditional silicon-based photoelectric detector is based on the photoelectric effect, and the light incidence higher than the specific frequency enables electrons to jump to a conduction band and become free carriers, so that current is generated; the detector obtains the corresponding optical power by measuring the current. The forbidden band width of silicon is 1.1eV, which corresponds to 1.1 μm of light wavelength, so that the traditional silicon-based photodetector has poor response to the infrared band, and is difficult to be directly applied to the communication band (mainly corresponding to 1.3 μm and 1.55 μm of light wavelength).

Ion implantation is an important doping technique in the semiconductor field. The ion implantation is to accelerate impurity ions by an electric field in a low-temperature and vacuum environment, so that the impurity ions obtaining kinetic energy directly enter the semiconductor material, and the impurity ions gradually lose energy by interaction with atoms in the semiconductor material after entering the material and finally stay in the semiconductor material.

Each semiconductor material has defects therein, which are derived from impurity ions, double holes, or surface reactions. When photons are incident, the presence of a defect state causes the defect state to absorb and generate free carriers, resulting in a current flow. Defect state absorption is one type of sub-bandgap absorption that enables a photodetector to respond to photons with energies less than its forbidden bandwidth. The traditional silicon-based photoelectric detector cannot detect optical signals in an infrared band or has weak response to the infrared band due to the limitation of a response mechanism.

Disclosure of Invention

The invention provides a method for improving the infrared response of a silicon-based detector by helium ion implantation, which utilizes the defect state absorption caused by the helium ion implantation in the silicon-based photodetector, can improve the infrared response of the traditional silicon-based photodetector, does not need to greatly change a peripheral reading circuit and a packaging mode, and is described in detail as follows:

a method of helium ion implantation to boost the infrared response of a silicon-based detector, the method comprising:

helium ions are implanted into a silicon material to generate a defect state, when the optical power incident on the silicon-based photoelectric detector changes, the admittance of a photosensitive area of the silicon-based photoelectric detector changes under the simultaneous action of the defect state absorption effect and the surface state absorption effect, and the monitoring of the silicon-based photoelectric detector on the optical power of an infrared waveband is realized;

the silicon-based photoelectric detector is a vertical coupling transparent photoelectric detector based on the surface state absorption principle, and comprises: photosensitive detector and signal readout circuit.

Furthermore, the photosensitive detector consists of a photosensitive surface, an oxide layer, a gold electrode and a substrate, and when an optical signal to be detected is incident on the photosensitive surface, the admittance of the device is changed through sub-band gap absorption.

In one embodiment, the helium ion implantation is performed by using a helium ion microscope, and the implantation is performed in a scanning manner by using an accelerating voltage of 30kV, wherein each implantation is performed for 0.25 × 0.25nm²Until the entire target implant area is traversed.

In one embodiment, the signal sensing circuit has a device admittance as the sensing signal,

the signal reading circuit consists of a trans-impedance amplifier and a phase-locked amplifier, the phase-locked amplifier provides alternating current driving voltage, a current signal is amplified by the trans-impedance amplifier and then input to a receiving end of the phase-locked amplifier for signal processing, and admittance change of a device is measured;

and calculating the optical power detected by the device according to the calibrated relation curve of the optical power and the admittance change.

Further, the method further comprises:

after helium ions are injected into the silicon-based photoelectric detector, the relation between the device admittance and the working frequency of a driving voltage source under different optical powers is obtained through testing, and the frequency with the most obvious admittance change is found as a working point;

after the working frequency is determined, the relation between the optical power and the admittance change under different wavelengths is calibrated again.

The technical scheme provided by the invention has the beneficial effects that:

1. before the invention, the silicon-based photoelectric detector has no response or weak response to the infrared band with the wavelength of more than 1.1 mu m, the sensitivity is poor, and the accuracy of optical power detection is greatly influenced by background noise; according to the invention, a defect state absorption mechanism is introduced into the silicon-based photoelectric detector through helium ion implantation, and the output signal is read out in a phase-locked manner, so that the infrared response of the silicon-based photoelectric detector is improved, the detection spectrum range of the silicon-based photoelectric detector is widened, and the application field is expanded;

2. the invention increases the signal-to-noise ratio of the device while improving the sensitivity of the detector, and improves the accuracy of the detection of the optical power of the silicon-based photoelectric detector; the method for implanting helium ions does not increase the complexity of a device structure and a reading circuit.

Drawings

FIG. 1 is a schematic diagram of a silicon-based photodetector with helium ion implantation and a schematic diagram of an optical microscope photograph of the silicon-based photodetector;

wherein, (a) is the schematic diagram of helium ion implantation silicon-based photodetector, the area of the silicon photosensitive region is 5m multiplied by 5 μm, the thickness is 220nm, the thickness of the oxide layer at the bottom of the photosensitive region is 3 μm, the thickness of the silicon substrate is 725 μm, titanium/gold electrodes are arranged at two sides of the photosensitive region, and helium ions are implanted into the photosensitive region from the top of the photosensitive region; (b) is an optical microscope photo of the silicon-based photoelectric detector.

FIG. 2 is a flow chart of a process for fabricating a silicon-based photodetector implanted with helium ions;

FIG. 3 is a diagram of a silicon-based photodetector testing apparatus implanted with helium ions;

FIG. 4 is a diagram showing the relationship between admittance and driving frequency of a silicon-based photodetector under different He ion implantation amounts in the absence of light;

FIG. 5 is a two-dimensional scanning graph of admittance and optical power of a silicon-based photodetector at a He ion implantation dose of 0.01ions/nm 2;

wherein, (a) is an admittance two-dimensional scanning diagram of the silicon-based photodetector when the He ion implantation amount is 0.01ions/nm 2; (b) is a two-dimensional scanning graph of the optical power of the silicon-based photoelectric detector when the He ion implantation amount is 0.01ions/nm 2.

FIG. 6 is a diagram showing admittance of a silicon-based photodetector at different driving frequencies and optical powers for a He ion implantation dose of 0.01ions/nm 2;

wherein, (a) is the relationship between admittance and driving frequency of the silicon-based photodetector under different optical powers when the He ion implantation amount is 0.01ions/nm 2; (b) the relationship between the admittance variation of the silicon-based photodetector and the optical power when the He ion implantation amount is 0.01ions/nm 2.

FIG. 7 is a diagram showing the sensitivity and responsivity of a silicon-based photodetector for different He ion implantation amounts;

wherein, (a) is the sensitivity of the silicon-based photoelectric detector under different He ion implantation amounts, and the dotted line is the sensitivity of the silicon-based photoelectric detector without implanted ions; (b) the responsivity of the silicon-based photoelectric detector under different He ion implantation amounts is shown, wherein the dotted line is the responsivity of the silicon-based photoelectric detector without implanted ions.

FIG. 8 is a graph of the response of a silicon-based photodetector with no implanted ions and implanted ions at 0.01ions/nm 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below.

In order to solve the problems in the background art, the embodiment of the invention utilizes the defect state and defect state absorption generated by injecting the helium ions into the silicon material, can enhance the infrared response of the silicon-based photoelectric detector, and broadens the detectable wavelength range of the photoelectric detector, thereby expanding the application range and application scene of the photoelectric detector.

The invention provides a method for improving the infrared response of a silicon-based photoelectric detector based on helium ion implantation, which has better compatibility with the traditional photoelectric detector technology and has application prospect and help for improving the photoelectric detector.

The general technical scheme of the invention is as follows: the helium ion implantation technology is utilized to improve the response of the silicon-based photoelectric detector in an infrared band. The silicon-based photoelectric detector is a vertical coupling transparent photoelectric detector based on the surface state absorption principle, and comprises: a photosensitive detector and a signal readout circuit; the photosensitive detector consists of a photosensitive surface, an oxide layer, a gold electrode and a substrate, and when an optical signal to be detected is incident on the photosensitive surface, the admittance of the device is changed through sub-band gap absorption (defect state absorption and surface state absorption); the signal readout circuit takes the device admittance as the readout signal.

The signal reading circuit is composed of a trans-impedance amplifier and a phase-locked amplifier. The phase-locked amplifier provides alternating current driving voltage, a current signal is amplified by the trans-impedance amplifier and then input to a receiving end of the phase-locked amplifier for signal processing, and admittance change of a device is measured; and calculating the optical power detected by the device according to the calibrated relation curve of the optical power and the admittance change.

Helium ion implantation is performed using a helium ion microscope. When helium ion implantation was performed, an acceleration voltage of 30kV was used. The whole device is implanted in a scanning mode, and each implantation is performed for 0.25 multiplied by 0.25nm²After a certain amount of lattice points are implanted, the lattice points are transferred to the next region to be implanted with the same area to continue implantation until the whole target implantation region is traversed. The implantation dose of helium ions can be controlled within a certain range, namely: the number of helium ions implanted per square nanometer area.

The first implementation mode comprises the following steps:

referring to fig. 2, when the light power incident on the silicon-based photodetector is changed by injecting helium ions into the silicon chip by using a helium ion microscope, the admittance of the photosensitive region of the device is changed due to the simultaneous effect of the defect state absorption effect and the surface state absorption effect. Based on the phenomenon, the silicon-based photoelectric detector can monitor the optical power of the infrared band.

Fig. 3 is a schematic diagram of an experimental apparatus for monitoring optical power of a silicon-based photodetector implanted with helium ions. The phase-locked amplifier outputs a sine voltage with variable frequency, the voltage is input from a titanium electrode at one end of the device to be used as a driving signal, and then the voltage is output through the titanium electrode at the other end of the device; the output signal is amplified by a trans-impedance amplifier (TIA) and then returns to the phase-locked amplifier for demodulation, and the demodulated value is converted to obtain the admittance of the device.

The second embodiment:

silicon-based photodetectors need to be recalibrated after helium ion implantation: the relation between the device admittance and the working frequency of the driving voltage source under different optical powers is obtained through testing, and the frequency with the most obvious admittance change is found as a working point; after the working frequency is determined, the relation between the optical power and the admittance change under different wavelengths is calibrated again.

Fig. 4 is a relationship between admittance and driving frequency of a silicon-based photodetector under different helium ion implantation amounts in the absence of light. A preliminary screening can be performed based on the characteristics of these curves to identify an appropriate helium ion implant dose.

FIG. 5 shows a helium ion implantation at 0.01ions/nm²A two-dimensional scan of the reflected optical power and admittance of the silicon-based photodetector. The position and the outline of the device electrode and the photosensitive area can be contrasted and confirmed by using the graph, and the test alignment is convenient.

FIG. 6(a) shows a helium ion implantation at 0.01ions/nm²The admittance of the silicon-based photoelectric detector under different optical powers is related to the driving frequency; FIG. 6(b) is the relationship between the admittance variation of the silicon-based photodetector and the optical power at the same implantation amount of helium ions at 500 Hz. Using fig. 6(a), the driving frequency at which the admittance change is most pronounced can be determined as the operating point; the optical power at 1550nm wavelength was calibrated to the change in admittance using FIG. 6 (b).

FIG. 7 shows the sensitivity and responsivity of silicon-based photodetectors under different amounts of implanted helium ions. By utilizing the two relations, the required helium ion implantation amount can be determined according to the requirements of different test environments on sensitivity and responsiveness.

FIG. 8 shows non-implanted and implanted helium ions at 0.01ions/nm²The response spectrum of a silicon-based photodetector. It can be seen from fig. 8 that the response of the device after helium ion implantation is better than that of the device during implantation in the whole test band, which shows that the helium ion implantation can indeed improve the infrared response of the silicon-based detector.

In summary, fig. 4 to 8 verify that the method of the present invention improves the responsivity of the detector in the infrared band from 1200 nm to 1800 nm.

In the embodiment of the present invention, except for the specific description of the model of each device, the model of other devices is not limited, as long as the device can perform the above functions.

Those skilled in the art will appreciate that the drawings are only schematic illustrations of preferred embodiments, and the above-described embodiments of the present invention are merely provided for description and do not represent the merits of the embodiments.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.