A Novel Si,-,Ge,/Si MOSFET

A novel Si,.,Ge, channel Metal Oxide Semiconductor field effect transistor ( MOSFET) is described. Si,,Ge, alloy used was grown by means of molecular beam epitaxy (MBE). The band structure with Si,.,Ge, shannel MOSFETis different from that with 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, orientation silicon wafers with resistivity of 2 ohm-cm were used. First, Si,.,Ge, (x=O.l-0.7) layers were grown, whose thickness was 0.5-0.8 nm. Then, silicon buffer layer was grown. After that, gate oxidelayer 15 nm thick was grown at a temperature of 800 'C. Following polysilicon growth, polysilicon was doped by implantation of phosphorus. The formations of source and drain were by implantation as well. The I- V curvesof output with different dopant concentration were obtained. The main direct current parameters of measured Si,.,Ge,/Si MOSFETare: the threshold voltage V, = -I.3V, the transconductance Gm=100-130 siemens, the breakdown voltage of source and drain is 13-1 6V.