A novel triple δ-doped GeSi heterostructure field-effect transistor

A novel SiGe/Si heterostructure field-effect transistor structure, utilizing triple δ-doped layers in SiGe quantum well as a conducting channel, is proposed and fabricated for the first time. A lower δ-doped layer on both sides of the SiGe layer as a diffusion buffer layer is used to improve the carrier confinement and suppress the boron out-diffusion. Experimental results show that the proposed device exhibits excellent properties of higher output current drivability enhanced extrinsic transconductance and linear operation over a wider dynamic range than the devices with single δ-doped layer using the same doping dose in the channel. A wide, uniform g_m distribution of 4V resulting from improved confinement, a high gate-to-drain breakdown voltage (> 20 V) and a high current density of 57 mA/mm were obtained at room temperature.