Computer Simulation To The Performance Of Hetero-junction InGaAs Infrared Detector

InP/InGaAs heterojunction photovoltaic infrared detector have a very good performance. InGaAs is semiconductor material of theⅢ-Ⅴfamily. Its bandgap and the corresponding cut wavelength are between InAs (3.5μm)and GaAs.(0.8μm).For InP/InGaAs heterojunction detector,it has a rise wavelength and a cut wavelength ,from 0.93μm to 1.7μm. So it is the compatible material to prepare the short-wave infrared detector. It can cover with the commonly used wavelength of optical communications.During the middle of the twenties century,there are many kind of detector materiel,such as InSb,HgCdTe,PtSi,InGaAs/InP. From every aspect , InGa As detector is so a direct bandgap,working in room temparture,high purity th at make ithas a very good performance,low cost and easy to produce. For the past ten years, with the development of opto-fiber corresponding InGaAs materiel and technology had a big accomplishment.Now many research institute can produce high performance InGaAs detector,which are widely used in military defense,atmosphere remote and so on.Now, the rapid development of detectors decided the practical study to materials and devices urgent need the theory analysis calculations which can guide the optimal device design, so InGaAs infrared detectors computer simulation design is absolutely necessary..This paper give a clear konwledge of the computer simulation of InGaAs infrared detectors about its per for man ce.And the analysis between the performance parameters and the materiel parameters.This research show the performance of N-p InP/In0.53Ga0.47As heterojunct ion detector under 300K working condition,and how the materiel parameter and noise mechanism influence the optimum value such as R0A,quantum efficiency,detectivity.The point is materiel parameter such as carrier density,width,multipled rate effect the detectivity by influencing the quantum efficiency and noise mechanism.Because the detectivity is the most important parameter of the detector,so we can view a detector by its detectivity.There are two optimum values,from the equation D ?∝ηR 0A,we know that R0A and quantum efficiencyη.R0A effect the detectivity by noise mechanism,and the quantum efficiencyηshows how strong the detector absorb the light.We draw the conclusion from computer simulation as follow:1. In photovoltaic infrared detectors, there are four basic noise mechanisms: Auger mechanism,tunneling mechanism,Radiation mecha nism,Generatio n-recombination mechanism.But in hete rojunction detector there are only two of them really work. Because the energy gap of heterojunction has a offset,that will reduce the diffusion current.But Auger mechanism and Radiation mechanism are root from diffusion current.So it means in het erojunction only Generation-recombination mechanism and tunneling mechanism paly an very important role.2. The type of the heterojuntion aslo effect the performance of the det ec tor.Such as the performance of N-p type is better than P-n type.Because th e detectivity of N-p type is large than the one of P-n type`s .The quantum efficiency of N-p type is higher than P-n type.This is because the light ab sorbtion of p type is higher than n type ,For the diffusion length of p type InGaAs is very large ,also the lifetime is large.For that reason the quantum efficiency is high.3. The surface recombination of p-type material is a important material para meter which impacts the performance of the infrared detector. The R0A will be reduced, and then the quantum efficiency and detectivity will reduce obviously if the surface recombination of p-type material is too high. Therefore, it is necessary to passivate the surface of p-type material in order to effectively reduce the surface recombination.4. The performance of N-p InP/InGaAs heterojunction is highly influenced by Generation-recombination mechanism,so we must concentrate on the materiel which will effect the it,such as carrier density ,surface recom bi nation rate.Because the light absorbed is limited by narrowband which is the band gap of InGaAs.And when the thickness of p type is go to mu ch,the detectivity will never go further more.5. when we had optimized the materiel parameter,we get the incident wavel ength of N-p type is around 1.6μm.We get the max value of the detectivity and the quantum efficiency is 63% and 2.61×1012cmHz1/2/W,which comp ared with the old one is 1.28×1012cmHz1/2/W.This tells us that to optimu m the materiel parameter is important.