Using a PLD BN/AlN composite as an annealing cap for ion implanted SiC

Localized doping in SiC is done by ion implantation because dopants do not diffuse at acceptable rates until the annealing temperature exceeds 1800°C. During this process, SiC surface has to be protected up to high temperatures. The authors found We have found a solution to this problem by capping the AlN cap with a BN cap and then, after the sample has been annealed, ion milling off the BN and etching off the AIN as before. In this paper they show that this cap can protect the SiC surface up to temperatures at least as high as 1700°C. This is done by observing the surface in a scanning electron microscope (SEM) after the wafer has been annealed and the caps have been removed. They also describe the properties of the BN layer that was deposited by pulsed laser deposition (PLD) by looking its surface in the SEM; examining its structure with Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and cross section transmission electron microscopy (XTEM), and determining if there was any chemical -intermixing of the layers using Auger electron spectroscopy (AES) depth profiling