High-Performance Ge MOS Capacitors by $\hbox {O}_{2}$ Plasma Passivation and $\hbox {O}_{2}$ Am

Very promising capacitance-voltage (C-V) characteristics of capacitors on both p- and n-type Ge substrates are demonstrated by using an in situ O₂ plasma passivation and an O₂ ambient annealing. The capacitors exhibited a small equivalent oxide thickness of ~1.5 nm and a low D_it (<; 6 * 10¹¹ cm^-2eV^-1) energy distribution covering the major part of the Ge bandgap (>; 0.51 eV). The surface potential modulation efficiency was estimated to be ~80% from Hatband to strong inversion on both types of Ge. C-V hysteresis was less than 10 mV with positive bias up to 1.5 V. A low gate leakage current density of <; 9 * 10^-8 A/cm² at V_FB ± 1 V indicates high quality of the HfO₂/GeO₂ gate stacks. Excellent comprehensive properties suggest that a combination of O₂ plasma passivation and O₂ ambient annealing provides a promising technology for GeO₂-based CMOS devices.