A study on Electrical Transport Properties of ZnTe buffer layer effect on Tellurium doped GaSb

Abstract

Among the III-V binary semiconductors, Gallium Antimonide (GaSb) has attracted considerable attention. Many of its interesting properties are directly associated with its very low effective electron mass and high mobility. Consequently, it is an important candidate in high speed applications in transistors and other devices.

Undoped GaSb is always p-type conductivity due to the native defect such as Sb vacancy. Therefore, to achieve n-type thin film with higher carrier mobility, high quality film growth is absolutely required.

This thesis presents the electrical transport properties for one typical set of Te-doped GaSb layers

ii) Type I has a X-ray linewidth of 970 arcsec, while Type II has 2 times smaller value (520 arcsec). The increase of electron mobility in Type II is ascribed to the suppression of defect scatterings by point defects and dislocations, which is consistent to the decrease of X-ray linewidth in Type II. The electron transport mechanisms of the two types of GaSb:Te layers can be explained by ionized-impurity scattering and dislocation scattering. Consequently, it is suggested that the ZnTe buffer layers effectively enhance the structural quality and carrier mobility in Te-doped n-type GaSb epitaxial layers, which will improve the fabrication of optoelectronic devices.

i) Type I has an electron mobility of 250 ㎠/V·s while Type II has 2.5 times larger value,(630 ㎠/V·s)

the one is normally grown on a GaAs substrate by molecular-beam epitaxy (Type I), and the other includes a ZnTe buffer between the GaSb:Te layer and the GaAs substrate (Type II) with the structural properties and investigated the effect of ZnTe buffer on the Te-doped GaSb epitaxial layers based on the two layer Hall effect model. The five major scattering mechanisms (ionized impurity, dislocation, piezoelectric, deformation potential and polar phonon) effects were considered.

By using this method, two types of GaSb:Te layers show extremely different electrical and structural properties