n-Type Doping in GaSb using Dimethyltellurium (DMTe) by Metalorganic Chemical Vapor Deposition (MOCVD)

Antimony-based III-V semiconductors grown either lattice matched or slightly strained on GaSb substrates have received much attention both for their potential applications as optical devices in the wavelength of 1-4 μm and for their potential use in tunnelling structures, exploiting the heterojunction offset with the InAs, GaSb, and AlSb material systems. Although investigations in laser diodes have been carried out by many groups, problems still remain with the growth of a device-quality GaSb layer. Undoped GaSb usually exhibits p-type conductivity, owing to native lattice defects including Sb vacancies and antisite defects, i.e., Ga atoms on Sb site, VGaGaSb. Group-VI elements such as S, Se, and Te are commonly used as n-type dopants in GaSb because elements such as Si and Sn are amphoteric and lead to heavily compensated p-type layers. Researchers have investigated the growth and electrical property of n-type GaSb by all the major techniques. However, group-VI elements have a high vapor pressure and a high segregation coefficient, making it difficult to control the electron concentration. Therefore, the growth of GaSb doped with Te is still challenging and worthy of in-depth exploration. In this work, dimethyltellurium (DMTe) has been used as a dopant for the MOCVD growth of GaSb. The physical properties of MOCVD-grown Tedoped GaSb on semi-insulating (SI) GaAs substrates are reported. The effects of dopant flow rate on growth rate, surface morphology, and electrical and optical properties have been determined.