Youngrak Park

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A large GaN-Schottky barrier diode (SBD) with a recessed dual anode metal is proposed to achieve improved the forward characteristics without a degradation of the reverse performances. Using optimized dry etch condition for a large device, the electrical characteristics of the device are demonstrated when applying the recessed dual anode metal and changing the recess depths. The device size and channel width are 4 mm2 and 63 mm, respectively. The 16-nm recessed dual anode metal SBD has a turn-ON voltage of 0.34 V, a breakdown voltage of 802 V, and a reverse leakage current of 1.82 μA/mm at -15 V. The packaged SBD exhibits a forward current of 6.2 A at 2 V and a reverse recovery charge of 11.54 nC.

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We present a method of forming shallow p-doping on a 4H-SiC surface by depositing a thin Al layer (d = 5 nm) and then thermally annealing it at 1000 °C for 10 min. A secondary ion mass spectrometry analysis of the annealed Al/SiC sample reveals an Al concentration in excess of 1017 cm−3 up to a depth of d ≤ 250 nm. I–V measurements and CV characterizations of Ti-SiC Schottky barrier diodes (SBDs) fabricated on a n-type SiC epi-wafer indicate that the shallow Al doping increases the built-in potential of the junction and the barrier height by ΔVbi=0.51 eV and ΔϕB=0.26 eV, respectively. Assuming a rectangular doping profile, calculations of the built-in voltage shift and the Schottky barrier height indicate that partial dopant activation (activation ratio ∼2%) can induce the observed barrier height shift. The shallow doping method was then used to fabricate junction terminations in SBDs which increased the breakdown voltage and reduced the reverse leakage current. Technology CAD simulations of the SBD with ...

AlGaN/GaN-on-Si Large Schottky Barrier Diode With Recessed Dual Anode Metal

Bonding-pad electrode-area-etched AlGaN/GaN on a Si-based Schottky barrier diode (SBD) is fabricated. Electrode mesa etching leads to reverse bias leakage current about one order of magnitude lower than that of SBD without electrode mesa etching, but forward currents do not vary greatly, compared with that in conventional SBD, which has no electrode mesa etching.

Surface Al doping of 4H-SiC via low temperature annealing

A 9.7-12.9 GHz monolithic microwave integrated circuit (MMIC) low-noise amplifier (LNA) is designed and fabricated using AlGaN/GaN 0.25 μm high electron mobility transistor (HEMT) on silicon carbide (SiC) technology. The LNA shows a noise figure of 1.7-2.1 dB with a small-signal gain of 20-26 dB across the 9.7-12.9 GHz frequency range. In continuous wave (CW) conditions, the saturated output power of 34 dBm is showed at 11.2 GHz and the output third-order intercept point (OIP3) of 42 dBm is also achieved at 11.4 GHz.

Low leakage current AlGaN/GaN on Si-based Schottky barrier diode with bonding-pad electrode mesa etching

Al2O3 passivation by thermal oxidation of aluminium on AlGaN/GaN high-electron-mobility transistors (HEMTs) without Al2O3 etching is proposed. The deposition of a 5-nm-thick Al film was carried out, followed by a lift-off process to remove Al from the ohmic and contact pad area. Subsequently, the Al film was annealed under O2 ambient. When the gate bias was −7 V, the gate leakage currents of a conventional nonpassivated HEMT, a surface-passivated Schottky-gate HEMT, and a surface-passivated MOS-HEMT were determined as 140, 96, and 4.1 µA/mm, respectively. The current collapse phenomenon in the Al2O3-surface-passivated devices was evidently suppressed compared with that in the nonpassivated HEMT.