Gate-Leakage and Carrier-Transport Mechanisms for Plasma-PH3 Passivated InGaAs N-Channel Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

Gate leakage mechanism of the HfAlO plasma-PH3 passivated and non-passivated In0.53Ga0.47As N-channel metal–oxide–semiconductor field-effect transistors (N-MOSFETs) have been evaluated, in order to correlate the quality of the oxide deposited with the gate leakage mechanisms observed. At temperatures higher than 300 K, trap-free space charge limited conduction (SCLC) mechanism dominates the gate leakage of passivated device but non-passivated device consists of exponentially distributed SCLC mechanism at low electric field and Frenkel–Poole emission at high electric field. This Frenkel–Poole emission is associated with energy trap levels of ∼0.95 to 1.3 eV and is responsible for the increased gate leakage of non-passivated device. In addition, the electrical properties of the non-passivated device has also been extracted from the SCLC mechanism, with the average trap concentration of the shallow traps given as 1.3×1019 cm-3 and the average activation energy given as ∼0.22 to 0.27 eV. The existence of these defect levels in non-passivated device can be attributed to the interdiffusion of Ga/As/O elements across the HfAlO/In0.53Ga0.47As interface. On the other hand, passivated device does not contain Frenkel–Poole emission nor exponentially distributed SCLC mechanism, indicating a reduction in traps in the bulk of the oxide. In addition, the temperature dependent characteristics of off-state leakage have also been evaluated to provide insight into the off-state mechanism. The off-state leakage of both passivated and non-passivated device is determined by junction leakage, with Shockley–Read–Hall mechanism being its main contributor, and has activation energy of 0.38 eV for passivated device and 0.4 eV for non-passivated device. From Id∝T-0.37 observed for passivated device, in comparison to Id∝T-0.18 for non-passivated device, we have further confirmed the phonon scattering dominance of the passivated device at high electric field.