Thin epitaxial Si films as a passivation method for Ge(100): Influence of deposition temperature on Ge surface segregation and the high-k/Ge interface quality

Epitaxial fully strained Si films are known to form an effective passivation of the Ge(1 0 0) surface. However, we show using low-energy secondary ion mass spectrometry (SIMS) that considerable Ge surface segregation occurs for Si films grown from SiH4 at 500 degrees C. In this study, we develop an alternative deposition process at 350 degrees C using Si3H8 which significantly decreases the Ge peak at the Si surface. We attribute this strong reduction mainly to the fact that growth at 350 degrees C from trisilane proceeds below the Si-H desorption temperature. Charge pumping measurements on n-type Ge devices show a reduction by approximately a factor three in the high-k/substrate interface trap density for the samples with 350 degrees C Si passivation, compared to those using a Si passivation deposited at 500 degrees C. (C) 2006 Elsevier Ltd. All rights reserved.