A novel Si/sub 1-x/Ge/sub x//Si MOSFET

Abstract

A novel Si/sub 1-x/Ge/sub x/ channel Metal Oxide Semiconductor field effect transistor (MOSFET) is described. Si/sub 1-x/Ge/sub x/ alloy used was grown by means of molecular beam epitaxy (MBE). The band structure of the Si/sub 1-x/Ge/sub x/ channel MOSFET is different from that of the silicon channel MOSFET. Because of this, the performance of the former is better than that of the latter. In the present study, 3-inch-diam, N-type, oriented silicon wafers with resistivity of 2 ohm-cm were used. First, Si/sub 1-x/Ge/sub x/ (x=0.1-0.7) layers were grown, with a thickness 0.5-0.8 nm. Then, a silicon buffer layer was grown. After that, a gate oxide layer 15 nm thick was grown at a temperature of 800/spl deg/C. Following polysilicon growth, polysilicon was doped by implantation of phosphorus. The formations of source and drain were by also by implantation. The I-V curves of output with different dopant concentration were obtained. The main direct current parameters of measured Si/sub 1-x/Ge/sub x//Si MOSFET are: the threshold voltage V/sub T/=-1.3 V, the transconductance G/sub m/=100-130 siemens, the breakdown voltage of source and drain is 13-16 V.