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AlGaN/GaN heterostructure field-effect transistors (HFETs) with three kinds of gate lengths were fabricated, and the theory of polarization Coulomb field (PCF) scattering with the electron systems in the AlGaN/GaN HFETs was studied. There are two methods of analysis and calculation of the PCF scattering in AlGaN/GaN HFETs: one is by considering the 2-dimensional electronic gas (2DEG) of the gate-source, gate-drain, and gate regions as three independent electron systems and the other is by considering the 2DEG of the drain–source channel as a unified electron system. The calculation and analysis of the additional polarization charges underneath the gate region for the prepared AlGaN/GaN HFETs indicate that the theory of PCF scattering in AlGaN/GaN HFETs with three independent electron systems is more accurate. [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]

In this study, a novel AlGaN/GaN heterostructure field-effect transistor based on open-gate technology was fabricated. Sample transistors of different structures and sizes were constructed. Through measurements, it was found that by changing the width of the opening, the threshold voltage of the device could be easily modulated across a larger range. The open-gate device had two working modes with different transconductance. When the gate-source voltage VGS ≤ − 4.5 V, only the open region was conductive, and a new working mechanism modulated the channel current. Corresponding theoretical analysis and calculations showed that its saturation mechanism was related to a virtual gate formed by electron injection onto the surface. Also, the gate-source voltage modulated the open channel current by changing the channel electron mobility through polarization Coulomb field scattering. When used as class-A voltage amplifiers, open-gate devices can achieve effective voltage amplification with very low power consumption. [ABSTRACT FROM AUTHOR]

This paper demonstrates the improvement of device linearity in AlGaN/GaN heterostructure field effect transistors (HFETs) using polarization Coulomb field (PCF) scattering and investigates the relationship between device linearity and PCF scattering under 10 and 20 V drain bias. The mobility of the gate-to-source region in AlGaN/GaN HFETs is calculated using the Monte Carlo method. We find that PCF scattering decreases with an increase in gate bias (from −3 to −0.5 V) under high field conditions, leading to lower gate-to-source resistance. Under 20 V drain bias, linearity is worse than under 10 V drain bias. The transconductance drop is significant in AlGaN/GaN HFETs, which damages linearity. By adopting an appropriate drain bias, PCF scattering can alleviate transconductance drop and improve the linearity of AlGaN/GaN HFETs. [ABSTRACT FROM AUTHOR]