Normally-OFF Al₂O₃/AlGaN/GaN MOS-HEMT on 8 in. Si with Low Leakage Current and High Breakdown Voltage (825 V)

Abstract

We report recessed-gate Al2O3/AlGaN/GaN normally-OFF metal–oxide–semiconductor high-electron-mobility transistors (MOS-HEMTs) on 8 in. Si. The MOS-HEMTs showed a maximum drain current of 300 mA/mm with a high threshold voltage of +2.4 V. The quite low subthreshold leakage current (∼10−8 mA/mm) yielded an excellent ON/OFF current ratio (9 × 108) with a small, stable subthreshold slope of 74 mV/dec. An atomic-layer-deposited Al2O3 layer effectively passivates, as no significant drain current dispersions were observed. A high OFF-state breakdown voltage of 825 V was achieved for a device with a gate-to-drain distance of 20 µm at a gate bias of 0 V.

Modelling and Simulation of Normally-Off AlGaN/GaN MOS-HEMTs

“…The main advantage of SiO 2 is high barrier value between conduction bands of GaN and dielectric layer [13]. The research on the use of other dielectric materials are conducted, particularly on the high dielectric constant materials (high-κ) such as aluminium oxide (Al 2 O 3 ǫ r =8-9) [14] and hafnium oxide (HfO 2 ǫ r =15-20) [15]. The use of dielectric layers with a high dielectric constant results in better conductivity modulation in the transistor channel and the increase of maximum current in the on-state.…”

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

“…[1][2][3] GaN growth on a Si substrate is one of the most useful methods for providing large-area GaN wafers at a low cost. [4][5][6][7][8] As aresult of several breakthroughs, 9,10 an AlGaN/GaN HEMT on Si demonstrated a breakdown voltage of over 1400 V. 10 Unfortunately, the large lattice and thermal expansion mismatches between Si and GaN produce high-density dislocations in a GaN layer. [11][12][13] Decreasing the dislocation density in a GaN layer has been a major issue because the dislocations are considered to deteriorate the reliability and life of devices.…”

Effect of Carbon Doping and Crystalline Quality on the Vertical Breakdown Characteristics of GaN Layers Grown on 200-mm Silicon Substrates

“…Therefore, GaN-on-Si wafers are considered to be quite promising for power device applications. [5][6][7][8][9][10] To obtain high breakdown voltage in AlGaN/GaN HEMTs, the GaN-based buffer layer needs to be highly semi-insulating to suppress the leakage currents with the applied voltages. Introducing acceptor-like deep traps by doping with iron or carbon is an effective approach, as the undoped GaN buffer shows n-type behavior because of residual donors such as silicon, background oxygen impurities, and nitrogen vacancies.…”