Anhuai Xu

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%.

Compound semiconductor nanotube materials grown and fabricated

A new GaAs/InGaAs/InGaP compound semiconductor nanotube material structure was designed and fabricated in this work. A thin, InGaAs-strained material layer was designed in the nanotube structure, which can directionally roll up a strained heterostructure through a normal wet etching process. The compound semiconductor nanotube structure was grown by gas-source molecular beam epitaxy. A good crystalline quality of InGaP, InGaAs, and GaAs materials was obtained through optimizing the growth condition. The fabricated GaAs/InGaAs/InGaP semiconductor nanotubes, with a diameter of 300 to 350 nm and a length of 1.8 to 2.0 μm, were achieved through normal device fabrication.

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.