Search

In this study, the ungated AlGaN/GaN devices with special mesa structures were designed. The hypothesis of effective width expansion was tested experimentally by using ungated samples with different sizes, and an empirical expression for calculating the conduction channel effective width was given according to the experimental results. Finally, split-gate AlGaN/GaN heterostructure field-effect transistors (HFETs) with different gate lengths were prepared, and the channel electron mobility of split-gate samples was calculated by using the empirical expression and polarization Coulomb field (PCF) scattering theoretical model. The results showed that, for split-gate AlGaN/GaN HFETs, with the increase in the gate length, the total amount of additional polarization charges underneath the gate increases, resulting in the enhancement of the PCF scattering intensity. [ABSTRACT FROM AUTHOR]

In this study, a split-gate AlGaN/GaN heterostructure field-effect transistor with an auxiliary gate was fabricated. Through experiment and analysis, it was discovered that by applying a constant potential (usually 0 V or negative potential) to the auxiliary gate, a negative bias can be formed between the auxiliary gate and the channel. This consumes the two-dimensional electron gas in the channel, leading to significant improvements in the saturation characteristics of split-gate devices. By applying different potentials to the main gate and the auxiliary gate, a variety of device working modes can be obtained, and the threshold voltage can be altered across a large range. These advantages make split-gate devices with auxiliary gates more suitable for increasingly complex integrated circuit applications. [ABSTRACT FROM AUTHOR]

The relationship between mobility and subthreshold swing (SS) of AlGaN/GaN HFETs was investigated at 10 and 20 V drain bias using the Monte Carlo method. We find that the polarization Coulomb field (PCF) scattering dominates the mobility at both 10 and 20 V drain bias. The channel carrier mobility is reduced as the gate bias becomes more negative, which reduces SS. The influence of mobility has not been considered in the 60 mV/dec rule, and PCF scattering is crucial for SS to be lower than 60 mV/dec in AlGaN/GaN HFETs. However, when the drain bias is 10 V, the CF scattering significantly diminishes SS. When the drain bias is 20 V, the SS barely decreases. Accordingly, a lower drain–source bias is needed to appropriately reduce SS. [ABSTRACT FROM AUTHOR]