High current density and high PVCR Si/Si 1−xGe x DQW RTD formed with quadruple-layer buffer

Abstract

s As a strain-relief relaxed Si 1-x Ge x buffer that is used for type II band offset formation, we have proposed a quadruple-Si 1-x Ge x -layer (QL) buffer where misfit dislocations are evenly distributed in the lower two interfaces and a buffer surface with good crystallinity was obtained. The crystallinity of the buffer surface does not degrade by high P doping with a P concentration of ∼10 19 cm -3 during the buffer growth. A vertical-type electron-tunneling Si/Si 1-x Ge x resonant tunneling diode (RTD) formed with the highly P-doped QL buffer exhibits a high current density and a high peak-to-valley current ratio (PVCR) value. A planer-type electron-tunneling Si/ Si 1-x Ge x RTD formed with the same buffer using tetramethyl ammonium hydroxide (TMAH) etching and polyimide insulator, which is better suited for device integration, also exhibits a high current density and a high PVCR value and good initial static performance reproducibility.