Shuxing Zhou

A physical evaporation synthetic route to large-scale GaN nanowires and their dielectric properties

Abstract Large-scale GaN nanowires (GNWs) were prepared by thermal evaporation of conventional GaN powders (CGPs) under controlled conditions without involvement of any template or patterned catalyst. The as-synthesized GNWs are about 30 nm in diameter and several hundreds of microns in length. The growth of GNWs is controlled by the conventional vapor–solid mechanism. Dielectric properties of GNWs and CGPs are measured in the frequency range of 10 2 –10 7 Hz. The data obtained indicate that the grain size of samples has great influence on the dielectric properties, where the corresponding mechanism is discussed.

Effects of buffer layer preparation and Bi concentration on InGaAsBi epilayers grown by gas source molecular beam epitaxy

The effect of using an In0.53Ga0.47As buffer layer on the crystalline quality of InGaAsBi epilayer with Bi concentration up to 3.1% grown by gas source molecular beam epitaxy was investigated. It is found that use of the buffer layer has a dramatic effect on the improvement of surface morphology, structural, electrical and optical properties of InGaAsBi epilayers. Bi incorporation in InGaAs up to a concentration of 3.1% causes no degradation of the electron mobility and induces p-type carriers that compensate the background n-type carriers resulting in mobility enhancement with increasing Bi concentration. With the buffer layer preparation, a maximum electron mobility of 5550 cm(2) V-1 s(-1) at room temperature is demonstrated in InGaAsBi with x(Bi) = 3.1%, which is the highest value reported in InGaAsBi with x(Bi) > 2.5%.

Growth and electrical properties of high-quality InGaAsBi thin films using gas source molecular beam epitaxy

The effects of Bi flux and In/Ga ratio on Bi incorporation and electrical properties of InGaAsBi grown by gas source molecular beam epitaxy were systematically studied. It is found that use of a low In/Ga ratio has an enhancement effect on the incorporation of Bi and its content increases linearly with Bi flux until reach a saturation. Incorporation of Bi induces p-type dopant that compensates the background electron concentration but does not degrade the electron mobility for the Bi content up to 6.2%. Up to 7.5% of Bi incorporation has been confirmed by Rutherford backscattering spectroscopy (RBS) and a maximum electron mobility of 5600 cm(2)& V-1.s(-1) at room temperature was achieved in InGaAsBi with x(Bi) = 6.2%, which is the highest value reported in InGaAsBi with x(Bi) > 5%

Bi-Induced Highly n-Type Carbon-doped InGaAsBi Films Grown by Molecular Beam Epitaxy

Carbon-doped InGaAsBi films on InP:Fe (100) substrates have been grown by molecular beam epitaxy. It has been found that Bismuth incorporation induces extremely high n-type carbon-doped InGaAsBi films and its electron concentration increases linearly up to 1021 cm3 (highest reported to date for n-type III-V semiconductor) with increased CBr4 supply pressure, implying InGaAsBi to be a prospective ohmic contact material for InP-based terahertz transistors. It also has been proved by secondary ion mass spectroscopy that the alloy composition of carbon-doped InGaAsBi is altered by the preferential etching effect of CBr4, but the etching effect on the Bi content is negligible.