Search

A modulated VT HEMT with improved gm flatness is demonstrated for high linearity application. The modulated VT HEMT was achieved by connecting two elements with different VT values in parallel along the gate width, realizing a flat resulting transfer curve, and the two different VT elements were fabricated by recessing part area of the barrier along the gate width under the gate region. The proposed HEMT shows a gate voltage swing as high as 5.4 V, a high drain current of approximately 2 A mm−1, and an fT/fmax of 63/125 GHz with a much flatter profile within the large gate voltage range. [ABSTRACT FROM AUTHOR]

We propose an innovative recessed float field plate (RFFP) structure for millimeter-wave AlGaN/GaN high-electron-mobility transistors (HEMTs). The reduced peak electric field contributes to a three-terminal breakdown voltage of 122–140 V for RFFP GaN HEMTs with LGD = 1.35 μm, which is found to increase from 84 to 101 V. The current collapse characteristic is also improved significantly. No obvious increase in parasite capacitance is observed after integrating the novel RFFP, thereby maintaining the high-frequency performance of GaN HEMTs. This technique is especially attractive for HEMTs of millimeter-wave frequency and above, and has great potential for applications. [ABSTRACT FROM AUTHOR]

In this paper, a normally-off AlGaN/GaN high-electron-mobility transistors (HEMT) fabricated using inductively coupled plasma (ICP) CF4 plasma recessing and an implantation technique is reported. A gate-to-channel distance of ∼10 nm and an equivalent negative fluorine sheet charge density of −1.21 × 1013 cm−2 extracted using a simple threshold voltage (Vth) analytical model result in a high Vth of 1.5 V, a peak transconductance of 356 mS/mm, and a subthreshold slope of 133 mV/decade. A small degradation of channel mobility leads to a high RF performance with fT/fmax of 41/125 GHz, resulting in a record high fT × Lg product of 10.66 GHz·µm among Schottky barrier AlGaN/GaN normally-off HEMTs with Vth exceeding 1 V, to the best of our knowledge. [ABSTRACT FROM AUTHOR]

A novel enhancement-mode (E-mode) AlGaN/GaN high-electron-mobility transistor (HEMT) has been fabricated, by combining nanowire channel (NC) structure fabrication and N2O (or O2) plasma treatment. A comparison of two NC-HEMTs with different plasma treatments has been made. The NC-HEMT with N2O plasma treatment shows an output current of 610 mA/mm and a peak transconductance of 450 mS/mm. The DIBL of the NC-HEMT with N2O plasma treatment is as low as 2 mV/V, and an SS of 70 mV/decade is achieved. The device exhibits an intrinsic current gain cutoff frequency fT of 19 GHz and a maximum oscillation frequency fmax of 58 GHz. [ABSTRACT FROM AUTHOR]

We demonstrate an enhancement-mode (E-mode) Al2O3/InAlN/AlN/GaN metal–insulator–semiconductor high-electron-mobility transistor (MISHEMT) with enhanced breakdown voltage. The threshold voltage Vth shifts from −7.6 to 1.8 V using fluoride-based plasma treatment. The gate leakage current and the buffer leakage current were reduced by the conduction band modulation of negative fluorine charges. The reduction in the buffer leakage current enhanced the breakdown voltage from 80 to 183 V with LGD = 3 µm. The fabricated E-mode MISHEMT with a gate length of 1 µm exhibits a respectable drain current of 416 mA/mm and a peak transconductance of 150 mS/mm. [ABSTRACT FROM AUTHOR]