Space Displacement Damage Characteristics On Semiconductor GaAs And InP Nanowires Irradiated By Protons

Compared with traditional communication technology,space laser communication technology has many advantages,such as large communication capacity,good confidentiality,small size and low power consumption.Therefore,it is the best solut ion for achieving high bit rate communication.As the core components of the satellite platform equipped with satellite laser communication system,optoelectronic devices such as lasers and detectors work in the space radiation environment.The displacement damage caused by particle radiation will adversely impact on the performance of these devices and affects on the reliability and stability of the entire laser communication system.The nanowire structure is the basic functional unit for the fabrication of nanowire optoelectronic devices.Ga As and In P nanowires are new types of III-V semiconductor nanostructure,which have many applications in the field of optoelectronic devices,such as nanowire photovoltaic cells,nanowire detectors(PIN,PN,MSM structured photodetectors,for example),and nanowire lasers.Studies have found that semiconductor materials of Ga As and In P have high response rates in the visible and near-infrared spectral regions,and also have strong radiation resistance.Currently,people's research on the anti-radiation properties of nanostructures is only theoretical,but the theoretical model of radiation damage of nanomaterials has not been established for quantitative research.In addition,in order to solve the service lifetime of nanowire devices in space engineering applications,the radiation resistance characteristics of nanowire structures must be studied.At present,the radiation resistance characteristics of Ga As and In P nanowire structures in photovoltaic devices have not been reported at home and abroad.In this thesis,based on the demand of optoelectronic devices in space applications and aiming at providing technical and theoretical support for semiconductor nanowires in space applications,the displacement damage characteristics of Ga As and In P nanowire structures are studied.The mainly concrete content are enumerated as follows:To quantify the displacement damage of nanowires caused by radiation,the study of displacement damage effects on nanowires caused by radiation was performed.And a model of displacement damage of fluorescent characteristics of nanowire materials was established.Based on the carrier rate equation,the relational expressions of the fluorescence intensity,carrier radiative recombination life,and non-radiative recombination life of the nanowires under the conditions of small injections were derived as a function of the integrated radiation fluence.This model was verified by proton irradiation experiments.The problem of redistribution of radiation displacement defect density under size effect was studied.Under small injection conditions,the expression of the relationship between the semiconductor nanowire minority carrier lifetime damage coefficient and diameter was derived.A Ga As nanowire minority carrier lifetime damage model based on nano-size effect and nanowire carrier dynamics was established.The physical mechanism of the anti-radiation properties of nanowires was discussed.The correctness of the model was verified by the simulation calculations and proton irradiation experiments.The problem of the degradation of the photoelectric performance of the nanowire photodetector caused by radiation was studied.And a displacement damage model of the photoelectric characteristics of the Ga As nanowire array structure was established.Based on this model,the expressions of the dark damage of the light-conducting Ga As nanowire array structure and the displacement damage of the photoelectric response were derived.The dark conductance and device performance of the Ga As nanowire array structure with radiation integral fluence are obtained through proton irradiation experiments.The law of change and the key physical quantities affecting the damage of the photoelectric characteristics of the light-conducting device are obtained.The influence of displacement damage on the steady-state output characteristics of nanowire lasers was analyzed.Based on the carrier dynamics equations of nanowire lasers,an analytical formula was given for the pump power threshold and output power of nanowire lasers as a function of the integrated radiation fluence,and a steady-state output damage model for nanowire lasers was established.The pump power threshold displacement damage and steady-state output power displacement damage of In P nanowire lasers based on nano-size effect were analyzed,and the change law of steady-state output power damage of nano-wire lasers with nano-wire size was given.The radiation resistance of In P nanowire array structures in photovoltaic cells was studied by proton irradiation experiments.The variation of photovoltaic performance parameters of In P nanowire array structures with radiation fluence in a typical satellite orbit was analyzed.The radiation resistance characteristics of nanowire array structure and bulk structure were discussed.This work is about the basic research of the influence of the displacement damage on III-V semiconductor nanowire structure in the space radiation environment.We are seeking a way to solve the basic scientific problem that nanowire structure needs to solve in space application field: the size effect of semiconductor nanowire and its radiation resistance characteristics.This work will also provide theoretical basis for quantitative analysis of nanowire optoelectronic devices in space radiation environment,and provides technical and experimental guidance support for protection and reinforcement design for optoelectronic devices.