Problems in low-temperature grown polycrystalline InAs layers on glass and their relief by inserting GaSbAs buffer layers

We investigated the thickness dependence of structural and electrical properties of polycrystalline InAs layers grown on glass substrates at a substrate temperature of 230 °C by molecular-beam deposition. Degradation in electron mobility with decreasing thickness is shown and is attributed not only to the decrease in crystallite size but also to the existence of a defective layer adjacent to the substrate. In order to investigate the effectiveness of GaSbAs as buffer layers on these problems, polycrystalline InAs layers of 0.1 μm thickness were gown with GaSbAs buffer layers of various thicknesses and alloy compositions inserted between the InAs layers and the substrates. It is shown that, in spite of the low substrate temperature of 300 °C and the thin thickness of 0.1 μm, the polycrystalline InAs film can exhibit an electron mobility as high as 600 cm2/(V s) by inserting a 0.5-μm thick GaSbAs buffer layer of an Sb composition around 0.6.

► Electron mobility of 100-nm thick InAs grown directly on glass was low.
► The insertion of GaSbAs buffer layers improved the electron mobility of the InAs top layer.
► As a result, the InAs grown at 300 °C exhibited an electron mobility of 600 cm2/(V s).