Trimethylaluminum-Based Atomic Layer Deposition of MO_2 (M=Zr, Hf) Gate Dielectrics on In_(0.53)Ga_(0.47)As(001) Substrates

摘要

As post-Si era for digital device is incipient, In_(0.53)Ga_(0.47)As is a good candidate among n-type active channels with high electron mobility but - unlike Si - it lacks a well-established technology for dielectric gating which may bear aggressive device scaling. Here we propose a viable route for the atomic layer deposition (ALD) of high-K dielectrics taking advantage from the well-known self-cleaning effect of the trimethylaluminum (TMA) precursor on the Ⅲ-Ⅴ compound surfaces. In this respect, the incorporation of Al_2O_3 cycles both as a pre-conditioning surface treatment and inside the ALD growth of a MO2 host matrix (M=Zr, Hf) is here investigated. A1:MO_2/In_(0.53)Ga_(0.47)As heterojunctions have been scrutinized by in situ spectroscopic ellipsometry and ex situ chemical depth-profiling analysis which validate a good physical quality of the oxide and elucidate the effect of the pre-conditioning cycles at the interface level. The resulting MOS capacitors have been characterized by means of multifrequency capacitance-voltage measurements and conductance analysis therein yielding a permittivity of 19±1 both for A1:HfO_2 and A1:ZrO_2 and similar electrical quality of the interfaces. On the other hand, A1:HfO_2 appears to be electrically more robust against leakage and endowed with a lower frequency dispersion in accumulation.