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This work reports on the extraction and simulation of the electron velocity–gate voltages relationship for sub-100 nm InAlN/GaN heterojunction field-effect transistors (HFETs). A peak electron velocity (ve) at an electron density (ns) of 0.41 × 1013 cm−2 was observed at 1.06 × 107 cm/s in an InAlN/GaN HFET with 60 nm gate length (Lg) by delay time analysis. The ve at a high ns of 1.5 × 1013 cm−2 was observed at 0.6 × 107 cm/s. This peak ve behavior is explained by polarization Coulomb field (PCF) scattering and optical phonon scattering based on a Monte Carlo method. As Lg scaled from 350 to 60 nm, the current gain cutoff frequency (fT) and transconductance (gm) were improved. However, the thermal performance was degraded with a bad figure of merit P150 °C. Although a weakening of the control capability of Vgs on ns (Δns/ΔVgs) was observed in the shorter Lg device, which leads to a decrease in device gm, the larger electron velocity by the increased lateral electric field (E) and the larger Δve/ΔVgs by the increased PCF scattering still enhance the peak gm. Results indicate that the enhancement of Δve/ΔVgs is a vital method to strengthen the modulation of the gate on current and to suppress the short channel effect in GaN HFET. Our work supports a deeper understanding and analysis of sub-100 nm InAlN/GaN HFET device performance and physical mechanisms. [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 mechanism of current modulation in the open region of split-gate AlGaN/GaN HFETs can be explained by the fringe electric field (FEF) effect and polarization Coulomb field (PCF) scattering effect for the applied biased split-gate. • Experimental results and TCAD simulation reveal the role of the PCF scattering in split-gate AlGaN/GaN HFETs. • The PCF scattering modulates the current by affecting the mobility of the two-dimensional electron gas (2DEG) and is closely related to the additional polarization charges generated by the inverse piezoelectric effect. • This study further promotes the research and application of split-gate AlGaN/GaN HFETs. In this study, we fabricated two similar split-gate AlGaN/GaN heterostructure field-effect transistors (SG AlGaN/GaN HFETs). However, minor variations in structural design resulted in substantial differences in the current–voltage characteristics. The mechanism of current modulation in the open region of the HFET can be explained by the fringe electric field (FEF) effect and the polarization Coulomb field (PCF) scattering for the applied biased split-gate. In particular, the effects of FEF and PCF scattering on the two-dimensional electron gas in the open region were analyzed separately when only the open region was on. Experimental results and TCAD simulation reveal the role of PCF scattering in SG AlGaN/GaN HFETs and provide evidence for the universality of PCF scattering in electronic devices with the AlGaN/GaN heterostructure. This study is meaningful for the structural optimization and electrical performance enhancement of SG AlGaN/GaN HFETs. [ABSTRACT FROM AUTHOR]

An InAlN/GaN MIS-HEMT with ZrO 2 gate dielectric layer and a Schottky-gate InAlN/GaN HEMT were fabricated. Subsequently, the influence of ZrO 2 gate dielectric layer on polarization Coulomb field (PCF) scattering in InAlN/GaN MIS-HEMT was studied. Compared with InAlN/GaN HEMT, the ZrO 2 gate dielectric layer in InAlN/GaN MIS-HEMT results in fewer additional polarization charge and higher two-dimensional electron gas density at the same gate-source voltage (V GS) conditions. Also, we established that both of these factors weaken PCF scattering intensity. However, the InAlN/GaN MIS-HEMT has a larger gate swing. Therefore, there is a smaller V GS was applied during regular operation of device. When the V GS is small, PCF scattering is the strongest scattering and play non-negligible impact in the size of total electron mobility. This study provides a new theoretical foundation for further enhancing the performance of InAlN/GaN MIS-HEMTs. • The influence of the ZrO 2 gate dielectric layer on PCF scattering in InAlN/GaN MIS-HEMTs was determined. • The ZrO 2 layer leads to fewer Δ ρ G and higher n 2 D E G at the same gate bias conditions, both of these factors weaken PCF scattering intensity. • When the gate bias is small, PCF scattering plays a dominant role in the magnitude of the total electron mobility. • The results of this study have providing a new theoretical basis for further enhancing performance of InAlN/GaN MIS-HEMTs. [ABSTRACT FROM AUTHOR]