Research On Fabrication Of High-Performance One-dimensional GaAs Photodetector

The carrier mobility and absorption coefficient of ?-? materials are higher than that of Si material.Therefore,III-V compound semiconductors material are widely considered to be a more promising candidate material for a new generation of optoelectronic devices to replace silicon material.As an important III-V compound semiconductor material,GaAs has high photoelectric conversion efficiency and moderate direct band gap.GaAs nanowires have the excellent properties of III-V semiconductor materials,as well as the unique properties of one-dimensional materials.Due to its extremely small size,remarkable quantum effect and other novel physical properties,GaAs nanowires have attracted the attention of a large number of researchers.At present,GaAs nanowires have been widely applied to many optoelectronic devices such as photodetectors,nano-lasers,and solar cells.Among them,photodetectors,as an important component of many optoelectronic devices,have become the main driving force for the development of science and technology.And photodetector plays an irreplaceable role in the fields of national defense,people's livelihood and industry.With the rapid development of technology,higher requirements are put forward for the performance of photodetectors.To promote the performance of photodetectors,the improvement of material conductivity is the main research direction.In this dissertation,GaAs nanowires and Si-doped GaAs nanowires with different doping concentrations were grown by molecular beam epitaxy.The conductivity of GaAs nanowires was improved by Si doping.Photodetectors of undoped and Si-doped GaAs nanowires with different doping concentrations were fabricated by micro-nano processing technology.We analyzed the influence of doping on the performance of GaAs nanowire photodetectors.The main work is as follows:(1)Undoped and Si-doped GaAs nanowires with different doping concentrations were grown on Si(111)substrates with VLS growth mechanism by MBE.The undoped and Si-doped GaAs nanowires were measured by SEM,XRD,Raman spectra and PL spectra.It was proved that the effective doping of Si in GaAs nanowires through analyzing the structure and luminescence mechanism.The carrier concentration and conductivity of the undoped and Si-doped GaAs nanowires were calculated by the FWHM of the PL spectra.It was confirmed that the electrical conductivity of the GaAs nanowires increases as the doping concentration increases.(2)The photodetectors of undoped and Si-doped GaAs nanowire with different doping concentrations were fabricated by micro-nano processing technology.We measured the electrical and photoelectrical characteristics of the devices.The results of electrical characteristics showed that the conductivity type of undoped and Si-doped GaAs nanowires were all p-type semiconductor properties.And the nonlinearity of the output characteristic curve indicates that there were Schottky barriers at the contact interface between the two ends of the nanowire and the metal electrode.When the laser wavelength is 532 nm,the bias voltage is-2 V and the power density is 1.66 m W/cm²,the results of photoelectric characteristics showed that the photocurrent and responsivity of the undoped GaAs nanowire photodetector are 2.03×10^-11 A and 5.24 A/W,respectively.The photocurrent and responsivity of the Si-doped GaAs nanowire photodetector can reach up to 5.32×10^-10 A and 129.9 A/W.The results showed that the performance of the Si-dope device was significantly improved.Therefore,the Si-doped GaAs nanowire photodetector will have a very broad application prospect in the field of miniaturization and high-performance detection.