Research On Epitaxial Growth Of Silicon-based ?-? Semiconductor Materials And Theoretical Modeling Of Electron Transport In Superinjection Process

Since the 1940s,information technology has made remarkable progress.Silicon-based VLSI technology in which electronics work as the information carrier has become very mature and become a major cornerstone of today's information society after development for over half a century.At the same time,optical communication and optical information technology using photons as carrier have also been developed rapidly,and have shown great advantages in many aspects such as high speed,broadband and strong anti-interference ability.Therefore,the combination of the advantages of telecommunication information technology and optical information technology through photoelectric integration has become a dream that people are striving to pursue.At present,significant progress has been made in the development of silicon-based passive photonic devices,silicon-based photodetectors and silicon-based optical modulators.However,due to the factors of silicon material such as its indirect band gap characteristics,the research progress of silicon-based lasers is relatively slow.The research of silicon-based lasers using silicon-based ?-? family materials,for instance silicon-based GaAs,is a very competitive scheme,and the development of silicon-based quantum dot lasers has achieved inspiring success.However,the fabrication of devices that have higher quality requirements for heteroepitaxy materials such as silicon-based quantum well lasers are still under arduous exploration.Based on this background,this paper has carried out the research on high-quality epitaxy growth of silicon-based ?-? semiconductor materials under the support of a relevant national project and a relevant Beijing municipal project,and has made certain progress.At the same time,this paper also contains the research on the improvement of the theoretical modeling of electron transport in the superinjection process.The superinjection effect,discovered by Professor Zhores I.Alferov,the founder of heterostructure physics,is one of the most important and decisive basic effects for semiconductor heterostructure lasers to operate continuously at room temperature,and naturally is one of the factors to be considered for improving the performance of silicon-based lasers.The discovery of superinjection effect is a landmark event in the development history of semiconductor heterostructure lasers.However,it is noteworthy that as an experimental physicist,Alferov only draws the corresponding conclusion based on the law of steady-state carrier distribution,not involving its specific injection process,thus no corresponding theoretical modeling of the volt-ampere characteristics has been established.Although people have studied the problem later,all the theoretical modeling occurred so far have not been able to give a satisfactory and reasonable interpretation of the above-mentioned volt-ampere characteristics.This part of the work in this paper is encouraged and inspired by Professor Alferov,supported by a relavant project of Natural Science Foundation of China and has made substantial progress,which is of important academic value and has guiding significance for the fabrication of high-performance silicon-based III-V group semiconductor lasers.The main achievements and innovations of this paper are as follows:1.On the basis of a series of research results on high-quality hetero-compatible epitaxy growth in the laboratory,further expanded thinking during research,a study on the correlation between dislocation density and surface linearity is conducted,and a theoretical modeling for optimization method of large-mismatched compatible hetero-epitaxial growth based on the dependence between dislocation density and mesa dimension is constructed.The construction work of the theoretical modeling consists of two parts:one is to construct an appropriate function form which contains enough variables to interpret the evolution law of correlation;the other is to propose a set of correlation evaluation methods which contain specific criteria and give the corresponding guiding principles for process optimization.Subsequently,the feasibility of the above theoretical modeling is validated based on the reported experimental data for Ge/Si heterogeneous compatible materials.2.On the basis of proposing optimization method of large-mismatched compatible hetero-epitaxial growth based on the dependence between dislocation density and mesa dimension,in order to further improve the quality of Si-based GaAs epitaxy materials using this optimization method,GaAs epitaxy layers on Si substrates that contains a series of different mesa dimension is grown by using three-step method combining cyclic annealing in MOCVD system and test work on the epitaxy samples is carried out.Part of the test results such as XRD,PL,AFM are obtained.The significant positive effect of reducing the mesa dimension of the substrate on the quality of the epitaxy layer is observed.Regretfully,due to the renovation of the laboratory and the impact of the recent epidemic,the testing is not completely done.It is believed that more definite and meaningful conclusions can be drawn after all the experiments is completed.3.The amorphous silicon buffer layer combined with three-step method was used to grow the GaAs epithelial layer during the previous research of the laboratory,and the dislocation density of 1.5 × 105cm-2 in the epitaxy layer was obtained.During the research of this paper,the repeatability of this method is verified experimentally by using different MOCVD device.The completed tests such as XRD,PL,AFM show that the quality of the epitaxy layer material obtained this time is comparable to that obtained by this method in the previous experiment,which indicates that the scheme of introducing amorphous silicon buffer layer into the growth process of GaAs on Si is strongly competitive.This part of the work needs further study due to the renovation of the laboratory and the recent epidemic situation.4.Research on the theoretical modeling of electron transport in superinjection process is carried out.Several key problems in the three existing theoretical models of electron transport in superinjection process(the Anderson diffusion model,the thermo-electron emission model and the tunnelling model)are found.The shortcomings of these theoretical models are explained and modified and,based on new and original understandings,these theoretical models are extended.The modifications and expansions include:a mistake of integral calculation in obtaining the portion of electron concentration within the energy region higher than the barrier tip is corrected;the effects of the shape of the barrier peak around the heterostructure interface on the electron concentration there and the electron transport characteristics are considered;the understanding of the electron transmissivity across the barrier peak in the Anderson diffusion model and the thermo-electron emission model is concretely deepened,and the corresponding expression is modified;the lopsided understanding that the diffusion motion mechanism could be simply replaced by the thermo-electron emission mechanism in the thermo-electron is corrected,and the Anderson diffusion model and the thermo-electron emission model are harmonically combined together by abstracting the reasonable aspects of the two models and sublating their cognitive defects;the concept of 'statistical intrinsic emission' is proposed for the first time and the effect of electron velocity in the 'statistical intrinsic emission' on the characteristics of heterostructure electron injection is revealed.At the same time,according to relevant new understandings,the theoretical model of electron transport in superinjection process involving the tunnelling effect is established.Eventually,a completely general theoretical model of electron transport in superinjection process with comprehensive consideration of the diffusion effect,the thermo-electron emission effect,the statistical intrinsic emission effect and the tunnelling effect is established.This work has solved several longtime-suspended basic scientific problems regarding the superinjection effect and has made the superinjection effect interpreted more scientifically and reasonably.