In0.53Ga0.47As(001)−(2x4) and Si0.5Ge0.5(110) surface passivation by self-limiting deposition of silicon containing control layers

Metal oxide semiconductor field effect transistors (MOSFETs) are diverging from the exclusive use of silicon and germanium to the employment of compound semiconductors such as SiGe and InGaAs to further increase transistor performance. A broader range of channel materials allowing better carrier confinement and higher mobility could be employed if a universal control monolayer (UCM) could be ALD or self-limiting CVD deposited on multiple materials and crystallographic faces. Silicon uniquely bonds strongly to all crystallographic faces of InGa_1-xAs, In_xGa_1-xSb, In_xGa_1-xN, SiGe, and Ge enabling transfer of substrate dangling bonds to silicon, which may subsequently be passivated by atomic hydrogen. Subsequently, the surface may be functionalized with an oxidant such as HOOH(g) in order to create a UCM terminating Si-OH layer, or a nitriding agent such as N₂H₄(g) in order to create an Si-N_x diffusion barrier and surface protection layer. This study focuses on depositing saturated Si-H_x, and Si-OH seed layers via two separate self-limiting CVD processes on InGaAs(001)-(2x4), and depositing a Si-N_x seed layer on Si_0.5Ge_0.5(110) via an ALD process. XPS in combination with STS/STM were employed to characterize the electrical and surface properties of these silicon containing control layers on InGaAs(001)-(2x4) and Si_0.5Ge_0.5(110) surfaces. MOSCAP device fabrication was performed on n-type InGaAs(001) substrates with and without a Si-H_x passivation control layer deposited by self-limiting CVD in order to determine the effects on C_max, frequency dispersion, and midgap trap states.