Controlled Synthesis And Photoelectronic Characterization Of GaSe Microbelts

Photodetectors,as a kind of important device for people to capture external information,are widely used in many fields such as defense military and industrial production due to their excellent photoelectric signal conversion capabilities.GaSe is a typical III-VI layered semiconductor compound,and it has received widespread attention due to its excellent photoelectricity such as suitable optical band gap,higher carrier mobility,etc.Herein,we report the controlled synthesis of GaSe microbelts through the vapor-liquid-solid?VLS?growth mechanism.The morphology,growth mechanism,photoelectric performance and other characteristics of GaSe microbelts were systematically researched and a GaSe microbelt-based high performance photodetector was fabricated.The specific research results are as follows.1. GaSe microbelts were controllable synthesized through chemical vapor deposition method by using Ga₂Se₃ and excess Ga as the mixture precursors.XRD,SEM and other characterizations showed that the excess Ga in the reaction worked as a catalyst and induced the growth of microbelt.The as-obtained products were characterized to be pure hexagonal GaSe with smooth surface and excellent crystallinity.EDS and XPS spectra verified the existence of a nanoscale amorphous Ga O_X layer on the surface of the microbelt,which may be caused by excessive Ga deposited on the surface of the microbelt and spontaneous oxidized in the air.The visible-near infrared absorption spectrum showed that the microbelt has obvious strong absorption in the visible light region,giving an optical band gap of about 1.78 e V,which is expected to be used in the field of visible light detection.2. A single GaSe microbelt-based photodetector was fabricated.The electrical characterization showed that the GaSe microbelt has obvious p-type semiconductor characteristics.The photodetector showed a responsivity of?3866 A/W and a photoconductive gain of 1.06×10⁴ under 450 nm?with the light intensity 9.47?W/cm2?illumination at a bias voltage of 3 V.The high gain arised from the built-in electric field formed between the superficial amorphous Ga O_X layer and the surface of the microbelt.When the photoelectron-hole pair is separated by the built-in electric field,the electrons are bound to the n-type Ga O_X layer,and the holes are left in the microbelt channel.This spatial separation significantly inhibited the recombination of carriers.The holes transporte in the microbelt and circulate many times,giving a very high gain.3. The flexible photodetector based on GaSe microbelt was fabricated using a flexible and transparent mica sheet as the substrate.The detector showed a good flexibility and potential application in the field of flexible optoelectronics.