Influence of crystal quality on the electronic properties of n-type 3C-SiC grown by low temperature low pressure chemical vapor deposition

Abstract

We analyze the influence of crystal quality on the electronic properties of 3C-SiC layers deposited by low-pressure chemical vapor deposition. Single crystalline films show good electronic quality and can be efficiently doped with NH3. The transition to nanocrystalline 3C-SiC, achieved by a decrease in deposition temperature from 1200 °C to 1100 °C, results in a decrease of the carrier mobility and an increase of the residual carrier concentration in nominally undoped layers. Comparative analysis by scanning electron microscopy, transmission electron microscopy, and secondary ion mass spectroscopy reveals an enhancement of the average oxygen concentration by almost two orders of magnitude and an accumulation of oxygen at crystal defects. The density and distribution of oxygen decorated defects are shown to be responsible for the increasing density of residual carriers in polycrystalline and nanocrystalline films. In single-crystalline films, the depth distribution of such defects explains the dependence of residual carrier density and mobility on the layer thickness.