Shallow doping effect of ZnO treatment using atomic layer deposition process on p-type In_0.53Ga_0.47As

The number of atomic layer deposition (ALD) cycles for ZnO treatment was changed to study its merits and demerits as a passivation layer prior to the deposition of a HfO₂ film on a p-type In_0.53Ga_0.47As substrate. Even a few cycles of ZnO ALD treatment was effective in improving the capacitance–voltage (C–V) characteristics by suppressing strong Fermi-level pinning, which occurred because of a high interface state density near the lower half of the In_0.53Ga_0.47As band gap. Increases in the number of ZnO ALD cycles induced an increase in the minimum capacitance and response of minority carriers at higher frequencies in the inversion region of the C–V characteristics. According to various temperature- and frequency-dependent C–V analyses, these changes were explained by the shallow p-type doping effect of Zn atoms in the In_0.53Ga_0.47As substrate. As a disadvantage, ZnO ALD treatment caused a slight increase in the dielectric leakage current. (paper)