Plasma-enhanced ALD growth of high breakdown field Ga2O3

Abstract

This study investigates the structural, chemical, and dielectric properties of sub-20 nm Ga2O3 thin films grown by plasma-enhanced atomic layer deposition at 250 °C using triethylgallium and oxygen plasma. The as-deposited films are amorphous and exhibit sub-nanometer surface roughness on c-plane sapphire and Si (100) substrates, with carbon impurity concentrations below the detection limit of x-ray photoelectron spectroscopy. Metal–insulator–metal capacitors fabricated on tungsten-coated Si substrates yield a relative dielectric constant of 11.05 and a maximum intrinsic breakdown field of 7.17 MV/cm, with leakage current remaining below 10−5 A/cm2 at electric fields up to 3.9 MV/cm. Quantitative analysis of the pre-breakdown current–voltage characteristics reveals that injection-limited current is the dominant conduction mechanism, while bulk-limited Poole–Frenkel and space-charge-limited currents are shown not to govern transport.