Preparation and electrical properties of InSb thin films heavily doped with tellurium, selenium and sulphur

Abstract

A method of controlled donor doping of flash-evaporated InSb thin films in the concentration range 10 17−10 19 cm −3 is described. When such films are regrown from the melt the electron concentration increases several times and the room temperature electron mobility increases by about an order of magnitude. The room temperature mobility of the regrown films is close to that observed in bulk InSb. The temperature dependence of the mobility between 80 and 700 K shows that barrier scattering plays an important role in all flash-evaporated and melt-regrown films with effective donor concentrations N d of 10 18 cm −3 or less. In the flash- evaporated films the barrier height increases from a value of 65 meV for N d = 10 17 cm -3 to 150 meV for N d = 9×10 18 cm −3. No such increase is observed in regrown films. This suggests that the barriers in the two types of films are different. The increase in electron concentration in regrown films is discussed and the most consistent explanation of the effect is that a large number of conduction electrons are trapped at grain boundaries in the flash-evaporated films. The application of the heavily doped melt-regrown InSb films as Hall generators is also discussed.