In situ etching-back processes for a sharper top interface in boron delta-doped diamond structures

One of the main challenges of delta-doping of diamond with boron resides in minimizing the width and optimizing the structural quality of the interface region between the heavily-doped ultra-thin layer and the non intentionally doped high mobility epilayers. In this work, we present an in situ etching-back approach to this problem. In particular, a careful SIMS profiling of the top interface shows that advanced gas switching procedures and adequate in situ O2 and H2 plasma etch steps lead to a rising depth lower than 2 nm per decade over 3 to 4 orders of magnitude of boron concentration. A specificity of the present work is that the multilayer structures were obtained without interrupting the microwave plasma during the whole process.

► Challenge of delta-doping of diamond is in reducing width and optimizing interfaces. ► Smart gas switching and in situ O2 and H2 plasma steps make sharp and thin interfaces. ► Multilayer structures were grown without plasma interruption during the process.