Semiconductor Materials - 12

Abstract

To advance transistor scaling in integrated circuits, semiconductor nanosheets with high crystallinity and surface flatness are essential. Theoretical study on electron mobility for 2 nm-thick nanosheets suggested that Ge(111) nanosheets may offer an order of magnitude higher than Si nanosheets [1]. However, fabricating such ultra-thin Ge nanosheets remains difficult, and no experimental validation has been reported.

This study explores a novel method based on prior work [2], which showed that vacuum annealing of plasma-nitrided GeN/Ge structures leads to selective nitrogen desorption and Ge recrystallization. In this study, we deposited GeN films on sapphire substrates and attempted to form Ge nanosheets via selective nitrogen removal. While Ge vanished after annealing at 700°C in the GeN/sapphire structure, the Si/GeN/sapphire structure showed nitrogen migration into the Si cap and Ge formation (Fig. 1). These results pave the way for fabricating ultra-thin and high-quality Ge nanosheets.