Study On Solid Source Molecular Beam Epitaxy Growth Of InGaAs Detector Materials

The ?-? semiconductor material InGaAs/InP plays an important role in device and practical applications.In the field of optical fiber communication and remote sensing,it often plays a key role as a light source and detector.The epitaxy technology of InGaAs materials in our country is still at a relatively low level in general.For example,some key performance such as background concentration,mobility,and minority lifetime of materials still have a certain gap with those grown by foreign countries.This dissertation focuses on the molecular beam epitaxy?MBE?growth of InGaAs/InP PIN detector materials,studying the basic photoelectric properties of InGaAs/InP materials,key growth processes and characterization of device materials.The main research results of the dissertation are as follows:1.High-quality InGaAs/InP MBE epilayers were obtained by optimizing the process parameters.The background concentration of InP reaches 1²×10¹⁴ cm^-3,the room-temperature and 77-K mobility are close to 5000 cm²/V·s and 100000 cm²/V·s,respectively;for In0.53Ga0.47As epilayers,the background concentration of reaches1×10¹⁵ cm^-3,and the room-temperature and 77-K mobility exceed 10000 cm²/V·s and64000 cm²/V·s,respectively.2.The measurement errors of the composition determination by photoluminescence?PL?and high-resolution X-ray diffraction?XRD?were evaluated.On the basis of that,the non-uniformity of epilayers was characterized and optimized.The experimental results show that the measurement errors of the two characterization methods on the AlGaAs material composition exceed±1%,and the true result of composition non-uniformity is basically covered by the measurement error.By appropriately increasing the temperature of the outer heater in the manipulator?10°C higher than the inner heater in the experiment?,the non-uniformity of the 4-inch AlGaAs composition was improved,and the 77-K mobility non-uniformity of the 3-inch GaAs/AlGaAs HEMT material was markedly improved.The non-uniformity of 4-inch and 3×2-inch In0.53Ga0.47As epilayers was studied.The results show that the measurement errors of the InGaAs composition by XRD are negligible,about±0.01%,so the XRD can be used to precisely measure the InGaAs composition.The material uniformity performed well.For example,the composition non-uniformity of the 4-inch epilayer is±0.1%,and the composition and doping concentration non-uniformity of the3×2-inch epilayer are±0.2%and±3.0%,respectively.3.For desorption processes of oxide on InP substrates,two methods of the desorption under P2 or As4 overpressure were evaluated.The InP samples were characterized by variable-temperature Hall tests,which were grown by the two methods.The results show that the parameter window of the desorption under P2 overpressures is relatively narrow,which means the parameters needs optimization;one the other hand,the parameter of desorption under As4 overpressure is reliablie,and the comprehensive electrical performance of samples grown by As4 overpressures is better.4.The anomalous arsenic?As?diffusion was observed at the InGaAs/InP interface.The samples were characterized by PL,XRD,3D atomic probe?3DAP?and scanning transmission electron microscopy?STEM?.The results show that in the InGaAs/InP sample grown by the P2-to-As2 switching process,we observed that As atoms can diffuse from the heterointerface into the lower InP by several hundred nanomters,forming a thick composition-graded InAsyP1-y layer.The anomalous diffusion process was explained.The P2-to-As4 switching process can effectively suppress the anomalous diffusion and result in a sharp heterointerface.The atomic distribution and material composition near the heterointerface of InGaAs/InP double heterojunction?DH?materials were characterized by secondary ion mass spectrometry?SIMS?and PL methods.The results show that for the interface between InP cap and InGaAs absorber,and for the interface between InGaAs absorber and InP contact,no obvious interface problems can be found by the two methods.5.To characterize the minority carrier lifetime of the InGaAs absorber layer in InGaAs/InP DH materials,the microwave photoconductivity decay??-PCD?technique with excitation wavelength of 904 nm was used,and theoretical analysis for measurement and experimentals were carried out.The results show that the high performance of the InP cap?specifically the minority carrier lifetime?is the one of the most basic premise for accurately extracting the?-PCD minority carrier lifetime of the InGaAs absorber.The?-PCD measurement results mainly reflect InGaAs if the measured value of the minority carrier lifetime is relatively large.The?-PCD minority carrier lifetime of the homemade lattice-matched InGaAs material(N_D=1×10¹⁵ cm^-3)is on the order of 1?s.The relationship between the two key material parameters–PL intensity and minority carrier lifetime–and the dark current of devices was discussed.The results show that there is a qualitative correspondence between the PL intensity,the minority lifetime of the material,and the dark current performance of the device.By comparing the performance of InGaAs/InP DH detector materials grown by different research institutes,it is demonstrated that the room-temperature PL performance of home-made materials is close to others,and the room-temperature dark current levels of the corresponding devices are equivalent,with a statistical result of around 20 nA/cm²@-0.1 ?.