Comparative study of trimethylaluminum and tetrakis(dimethylamido)titanium pretreatments on Pd/Al₂O₃/p-GaSb capacitors

The effectiveness of trimethylaluminum (TMA) and tetrakis(dimethylamido)titanium (TDMAT) pretreatments on GaSb substrates were compared by examining the interfacial and capacitance-voltage (C-V) characteristics of Al₂O₃/p-type GaSb capacitors. In addition, for sample preparation, the temperature-dependent surface reactivity of GaSb was confirmed by examining the impact of the atomic layer deposition (ALD) loading temperature (stand-by temperature in air). An increase in the loading temperature from 65 to 150 °C in air ambient degraded the interfacial and C-V properties, which confirms the importance of the processing temperature for GaSb-based devices. Both in situ TMA and TDMAT pretreatments at 65 °C prior to the ALD of Al₂O₃ (150 °C) were effective in decreasing the amount of the interface oxide and the interface state density. While a similar degree of frequency dispersion in the C-V accumulation region was observed in the ALD-Al₂O₃/GaSb capacitor samples with and without TMA pretreatment, it largely increased for the TDMAT-pretreated sample, probably due to the formation of a Ti-oxide interlayer.