Effects of Al addition to Si-based flux on the growth of 4H-SiC films by vapour–liquid–solid pulsed laser deposition

Abstract

The stabilizing effect of Al addition to Si-based flux on 4H-type SiC has recently become a well-known phenomenon as it is commonly found in solution growth for bulk wafer use and in the vapor–liquid–solid (VLS) mechanism for epitaxial thin films. To understand its mechanism, in this study, we investigated the Al additive effects on VLS pulsed laser deposition (PLD) of SiC films on 4° off 4H-SiC (000−1) substrates, systematically varying the Al content in the Si flux. The inclusion of 3C-type SiC in the films tended to decrease as the Al content in the flux increased. On the other hand, a sizable amount of Al, ∼10²⁰ cm⁻³, was necessarily incorporated as a dopant homogeneously into the SiC films, giving a good linear relationship between the Al density in the SiC films and the Al content in the flux. In situ observation of a flux/SiC growth interface with a confocal laser scanning microscope technique revealed that the Al addition induced a well-regulated step-flow growth even at a temperature as low as 1300 °C, which is favoured for the selective growth of the 4H-type SiC, succeeding to the 4H stacking sequence of the seed substrate.