Computer Simulation To Homo-junction InGaAs Photovoltaic Infrared Detector

InGaAs is semiconductor material of the Ⅲ-Ⅴ family. Its bandgap andthe corresponding cut wavelength are between InAs and GaAs. So it is thecompatible material to prepare the short-wave infrared detector. It can coverwith the commonly used wavelength of optical communications because thatthe bandwidth of In0.53Ga0.47As is 0.75eV and the corresponding cutwavelength is 1.7μm. Moreover, InGaAs can match the InP fully, therefore, itcan be grown a high-quality extension layer on InP underlay, and produced ahigh-quality device. In addition, InGaAs can also have a very highperformance advantages at room temperature ,which make it out ofrefrigeration constraints. Meanwhile, InGaAs device has shown higherperformance than HgCdTe devices when the detection wavelength is under2.5μm.Now, the rapid development of detectors decided the practical study tomaterials and devices urgent need the theory analysis calculations which canguide the optimal device design, so InGaAs infrared detectors computersimulation design is absolutely necessary. The paper analyzes the materialsparameters and device parameters of the homogeneous InGaAs photovoltaicinfrared detector through computer simulation. We focus on analysising andresearching the relationship between the detector performance parameters andthe semiconductor materials parameters. We will adopt the analysis of thematerial parameters to enhance and improve R0A and quantum efficiency, andimprove the detectivity. The optimal material parameters for homogeneousInGaAs photovoltaic infrared detectors can be found to give the experimentsworkers a good direction, greatly reducing the number of experiments toimprove the efficiency of experiments.The most important parameter of demarcating the detector performance isthe detectivity, and then R0A and quantum efficiency is an important parameterof impacting the detectivity, therefore, these two aspects will also present thepaper. On the one hand, restraining the all kinds of noise mechanisms as soonas possible to reduce the influence of noise on device performance, andthereby to improve R0A;on the other hand, it is to enhance the quantumefficiency. The quantum efficiency is determined by the numbers of how manycarriers caused by light are absorbed by device. R0A and quantum efficiencyare both related tightly with the material parameters as incident face, materialthickness, surface recombination velocity and so on. Consequently, the choiceof material parameters has great impact on R0A and quantum efficiency.Material parameters can be divided into two categories, one is that theparameters will be determined, such as band gap Eg and effective quality m*,when the temperature and the material composition are determined. The otheris that the materials, such as the carrier concentration of materials andmaterial thickness, can be controlled artificially in the process of preparing thematerials and producing the device. Based on the computer simulation, theconclusions are drawn as follows.1. In photovoltaic infrared detectors, the four basic noise mechanisms(Auger mechanism, Radiation mechanism,Generation-recombination mechanism, and tunneling mechanism) arerelated to the material parameters directly and impact the deviceperformances together.2. It can be found that material composition, temperature, and carrierconcentration impact the Auger noise mechanism together. Changing thematerial parameters properly can restrain the Auger noise and improve thedevice performance. It is also can be found that the restraint area ofdifferent material parameters on Auger noise mechanism is different, theperformance parameters of detector can be improved by choosing thematerial width reasonably, the carrier concentration in different layer andpassivation processing of the device.3. Because the light absorption of p-region is stronger than the one ofn-region, the detectivity under the condition that light incidences fromp-region surface is higher than the one under the condition that lightincidences from n-region surface obviously.Light absorption under thecondition that light incidences from the p-region surface is strong than theone under the condition that light incidences from the n-region surfaceobviously. The reason is that why the carriers caused by injection of lightare transited in the material is the result of diffusion of the minority carrier.Because the diffusion length of electron is larger than the width ofmaterial greatly, the lifetime of it is longer, and the recombinationprobability is little relatively, the electron in the p-region can diffuseadequately with never recombination. On the contra, the reason that thediffusion length of hole in n-region is close to the width of material, andlifetime of hole is little relatively makes the holes be recombined untilthey diffuse to the p-n junction. The electron can be absorbed in theneutral area adequately when the light incidences from the p-regionsurface, while when the light incidences from the n-region surface, theintensity of light is depleted in n-region at first, and then the one arrivingto the p-region is little relatively, thereby, the quantum has been reduced.then the one arriving to the p-region is little relatively, thereby, thequantum has been reduced.4. The surface recombination of p-type material is a important materialparameter which impacts the performance of the infrared detector. TheR0A will be reduced, and then the quantum efficiency and detectivity willreduce obviously if the surface recombination of p-type material is toohigh. Therefore, it is necessary to passivate the surface of p-type materialin order to effectively reduce the surface recombination.5. The changing of surface recombination and material thickness in p-regionhardly impact the performances of device when the carrier concentrationin n-region is higher then the one in p-region under the condition that theincidence light is from the p-region surface. however, the increasing of thesurface recombination and material thickness will both reduce thedetectivity accordingly. Then we must consider the role of these twoparameters, but also its optimized.6. After the material parameters have been optimized, the detectivity is1.7856×1012cmHz1/2/W at 1.4μm as the light incidences from the p-region,however, the detectivity is 9.516×1011cmHz1/2/W at 1.59μm as the lightincidences from the n-region. Thus, in p-n homostructure, the maximum ofdetectivity can be got under the condition that the incidence light is fromthe p-region surface.