Carrier transfer effect on transport in<i>p-i-n</i>structures with Ge quantum dots

Abstract

Coulomb charge accumulation and carrier transfer by valence band states of Ge quantum dots (QDs) embedded in the intrinsic region of Si $p$-$i$-$n$ structures are studied by admittance and photocurrent spectroscopy, capacitance--voltage techniques, and Raman investigations. The effect of hole accumulation on the shape of direct current--voltage characteristics was found at temperatures 200 K. A blockade of conductivity via wetting layer (WL) states due to a positive charge trapped in QDs was observed. The effect was explained by thermally activated charge carrier transfer between QD and WL states.