P-type delta-doped SiGe/Si heterostructure field effect transistors
P-type SiGe/Si HFETs with different position of the δ-doped layer in the SiGe channel are reported for the first time. For the same device structure with a 1×100 µm2 gate, bottom-delta-doped-channel devices display a wide and flat range of uniform gm distribution of 1.4 V, and 0.9 V in top-delta-doped-channel devices. Compared to the latter devices, a high gate-to-drain breakdown voltage (>25 V) due to a better carrier confinement together with a higher current density for the bottom-delta-doped-channel devices was obtained at room temperature, which is expected to provide an additional degree of freedom for Si-based device applications.
