Preparation And Study Of Ga₂O₃ Microbelt And Its Solar-blind Ultraviolet Detectors

Ultraviolet detection technology is another dual-use technology that follows infrared detection and laser detection.With broad application prospects in missile early warning,space communication,fire early warning,high-voltage corona discharge detection,engineering monitoring,pollution prevention and so on,ultraviolet detectors based on wide bandgap semiconductors have been focused due to their natural visible light-blind,no need for expensive filters and high-voltage power supply,small size,light weight,strong electromagnetic resistance and radiation resistance in recent years.β-Ga₂O₃ is one of the most splendid candidates,which has the advantages of intrinsic straight solar-blind and can prepare solar-blind ultraviolet detectors without component adjustment.Compared to thin films and bulk materials,one-dimensional micro/nano materials retain the basic physical and chemical properties of them,while two dimensions of micro/nano materials are very small,which exhibits some unique properties and are expected to be used in fields such as micro/nano integrated devices,flexible devices,wearable devices.Currently,β-Ga₂O₃ solar-blind ultraviolet detectors with high response have been continuously reported,but there are still some problems to be solved in related research.Firstly,surface oxygen vacancy defects have important impacts on the performance of devices,but the means of regulating oxygen vacancy are very limited,and most methods cannot directly be operated on devices.Secondly,β-Ga₂O₃ self-power detectors are mainly based on pn heterojunction,whose process of preparation often requires high temperature and which faces problems such as poor interface quality,interfacial ion diffusion or non-uniformity.In response to the mentioned issues,a series of relevant research was conducted,the results achieved are as follows:（1）Material growth and device preparation:β-Ga₂O₃ microbelts were grown by chemical vapor deposition（CVD）.By controlling the growth conditions of CVD,especially the gas flow field,β-Ga₂O₃microbelts with high crystal quality,uniform morphology and high yield were prepared.By exploring the preparation conditions of the device,solar-blind UV detector based onβ-Ga₂O₃microbelt with stable metal-semiconductor contact was prepared,and the device with stability and repetitiveness was obtained.（2）Regulation of oxygen vacancy:By using HCl solution as the modifier and adjusting the treatment time,the oxygen vacancy regulation method which can be directly used in solar-blind UV detectors based onβ-Ga₂O₃microbelts was successfully realized.The photocurrent of the device can be increased effectively when the processing time is within 10 s～3 min.When the processing time is 1 min,the dark current of the device decreases,the photocurrent increases,and the descending time is shortened.X-ray photoelectron spectroscopy shows that after HCl treatment,the surface oxygen vacancy concentration ofβ-Ga₂O₃ microbelt increases,which may be the main reason for the improvement of device performance.（3）Construct heterojunction withβ-Ga₂O₃ microbelt:Firstly,β-Ga₂O₃ microbelts were prepared,and then Se material was selected as p-type material.By vapor deposition method,Se was deposited on one side ofβ-Ga₂O₃ microbelt to obtainβ-Ga₂O₃/Se heterojunction self-powered UV detector.The photocurrent of the device can reach 3 n A at 254 nm.