Spectroscopic ellipsometry (SE) together with the optical transmission method is successfully used to determine refractive index n and absorption coefficient α of undoped gallium nitride film over spectral range 0.78–4.77 eV photon energy. The SE measurement carried out at angle incidence 60° 1.5–4.77 energy 0.78–3.55 range. obtained by both methods show unique results in overlap wavelength region. Refractive found follow Sellmeir dispersion relationship n2(λ)=2.272+304.72/(λ2−294.02) below...

Surface passivation effects were studied on AlGaN/GaN high-electron-mobility transistors (HEMTs) using SiO2, Si3N4, and silicon oxynitride (SiON) formed by plasma enhanced chemical vapor deposition. An increase of IDmax gmmax has been observed the passivated (SiO2, Si3N4 SiON) HEMTs when compared with unpassivated HEMTs. About an order magnitude low IgLeak three orders high was SiO2 HEMTs, respectively, The is due to occurrence surface related traps, which confirmed observation kink...

A single crystal GaN thin film was successfully grown on a Si (111) substrate by means of atmospheric pressure metalorganic chemical vapor deposition. Though there is large difference in thermal expansion coefficients between and Si, an intermediate layer consisting AlN AlGaN improved the quality reduced meltback etching during growth. Pits cracks were not observed mirror-like surface obtained. The full-width at half maximum (FWHM) double-crystal X-ray rocking curve for GaN(0004) 600 arcsec....

The electrical properties of electron beam (EB) evaporated silicon dioxide (SiO2)/n-GaN, plasma enhanced chemical vapor deposited (PECVD) SiO2/n-GaN, and PECVD nitride (Si3N4)/n-GaN interfaces were investigated using high frequency capacitance–voltage measurements. Compositions the insulating layers (SiO2 Si3N4) analyzed x-ray photoelectron spectroscopy. Metal-insulator-semiconductor structures fabricated on metalorganic deposition grown n-type GaN EB, SiO2 Si3N4 layers. Minimum interface...

Enhancement of breakdown voltage (BV) with the increase AlN buffer layer thickness was observed in AlGaN∕GaN high-electron-mobility transistors (HEMTs) grown by metalorganic chemical vapor deposition on 4in. Si. The enhancement device performance (200 and 300nm) is due to reduction electrically active defects from Si substrate. confirmed x-ray rocking curve measurements. Not much change has been ON-state BV (BV:ON) values except devices 500-nm-thick layer. About 46% OFF-state (BV:OFF) 200μm...

An InGaN multiple-quantum-well light-emitting diode (LED) containing a GaN/AlGaN distributed Bragg reflector has been grown on sapphire substrate by metalorganic chemical vapor deposition. Comparing with the conventional LED, output power improved from 79 to 120 μW under 20 mA direct current biasing condition and external quantum efficiency also 0.16% 0.23% 10 dc current.

The high-electron-mobility transistors (HEMTs) have been demonstrated on both sapphire and semi-insulating (SI) SiC substrates, the dc characteristics of fabricated devices were examined at temperatures ranging from 25 to 500 °C. decrease in drain current transconductance with increase temperature observed. ratio was similar for HEMTs SI–SiC substrates above 300 showed better after being subjected thermal stress up Although SiC-based °C, compared sapphire-based HEMTs, observed For...

We report on the studies of temperature dependence gate–leakage current in AlGaN/GaN high-electron-mobility transistors (HEMTs) for range 20–400 °C. The results show that HEMTs at subthreshold regime (VGS=−6.5 V) have both negative and positive trends. It has been observed leakage decreases with up to 80 Above °C, increases temperature. activation energy +0.61 eV is due impact ionization. −0.20 surface related traps, −0.99 assisted tunneling mechanism. drain voltage a fixed drain–leakage...

Al x Ga 1−x N/GaN (0.20⩽x⩽0.52) heterostructures (HSs) were grown on a sapphire substrate by atmospheric pressure metalorganic chemical vapor deposition with good uniformity and two-dimensional-electron-gas (2DEG) mobilities of 936, 1163, 1310, 1274, 911 cm2/V s for different-Al-contents 20%, 27%, 34%, 42%, 52%, respectively. 2DEG mobility increase up to the content 34% then it slowly decreases high Al-content AlGaN/GaN HSs. An sheet carrier density has been observed. A small hump...

We report significantly improved characteristics of InGaN multiple-quantum well blue and green light-emitting diodes (LEDs) on Si (111) substrates using metalorganic chemical vapor deposition. A high-temperature-grown thin AlN layer AlN/GaN multilayers have been used for the growth high-quality active substrate. The LED exhibited an operating voltage 4.1 V, a series resistance 30 Ω, optical output power 18 µW peak emission wavelength 478 nm with full width at half maximum 22 20 mA drive...

Al 0.26 Ga 0.74 N ∕ heterostructures with 1-nm-thick AlN interfacial layers were grown on 100-mm-diam epitaxial AlN/sapphire templates and sapphire substrates by metalorganic vapor phase epitaxy. It was found that significantly enhanced the electron mobility of two-dimensional gas (2DEG) confined at GaN channel. This can be explained high-crystal-quality channel realized use as substrates. The very high Hall mobilities approximately 2100cm2∕Vs room temperature 17000cm2∕Vs 77K a 2DEG density...

We report on the high-performance of InGaN multiple-quantum well light-emitting diodes (LEDs) Si (111) substrates using metal-organic chemical vapor deposition. A high-temperature thin AlN layer and AlN-GaN multilayers have been used for growth high-quality GaN-based LED structure substrate. It is found that operating voltage at 20 mA reduced to as low 3.8-4.1 V due formation tunnel junction between n-AlGaN n-Si substrate when 3 nm. Because has a better thermal conductivity than sapphire,...

A recessed gate high electron mobility transistor (HEMT) has been fabricated with AlGaN/GaN heterostructure on a sapphire substrate using metalorganic chemical vapor deposition. Capacitance-voltage (C-V) and Shubnikov-de Haas measurements have shown the formation of two-dimensional (2-D) gas (2DEG) at Al/sub 0.11/Ga/sub 0.89/N/GaN heterointerface. 2DEG 12000 cm/sup 2//V-s sheet carrier density 2.8/spl times/10/sup 12/ -2/ was measured 8.9 K. The 0.26/Ga/sub 0.74/N/GaN HEMT structure showed...

Schottky diodes of Ti, Pd, and Ni/n-Al/sub 0.11/Ga/sub 0.89/N have been fabricated the barrier heights were measured to be 0.60, 0.95 0.97 eV using current-voltage (I-V) measurements 0.67, 1.15 1.22 capacitance-voltage (C-V) measurements. Annealed are show higher I-V C-V when compared with as-deposited Ti except high temperature annealed (450/spl deg/C/30 min-500/spl deg/C/1 hr) diodes. The height Ti/n-Al/sub increases up annealing 350/spl deg/C/5 min it decreased for temperatures. 150/spl...

A single crystal GaN thin film was successfully grown on a Si(111) substrate by means of atmospheric-pressure metalorganic chemical vapor deposition. An intermediate layer consisting AlN and AlGaN improved the quality Si with mirror-like surface reduced pits cracks over surface. The full width at half maximum (FWHM) double-crystal X-ray rocking curve for GaN(0004) 600 arcsec. Photoluminescence measurement 4.2 K nondoped revealed sharp band-edge emission FWHM 8.8 meV, which is narrowest value...

High-electron-mobility transistors (HEMTs) have been demonstrated on both AlN/sapphire templates and sapphire substrates, the dc characteristics of fabricated devices were examined at room temperature. Better with high extrinsic transconductances drain current densities observed in HEMTs grown when compared substrates. Extrinsic 214 137 mS/mm for Wg/Lg=15/2 μm substrates achieved, respectively. The enhancement small variations threshold voltage (⩽130 mV) is due to reduction dislocation...

A method of analysis spectroscopic ellipsometry (SE) measurement data is proposed for AlxGa1−xN/GaN heterostructures grown on sapphire substrates. The SE measured at three angles incidence, 40°, 50°, and 60°, are simultaneously fitted assuming the dielectric function to consist a Sellmeir dispersion equation free-exciton absorption term. refractive index n extinction coefficient k undoped AlxGa1−xN films determined in spectral range 1.5–4.13 eV photon energy. transition energy free exciton,...

We report the characteristics of InGaN multiple-quantum-well (MQW) green light-emitting diodes (LEDs) on Si (111) substrates. The MQW LEDs were grown by metalorganic chemical vapor deposition using Al0.27Ga0.73N/AlN intermediate layers. LED showed an operating voltage 7 V, a series resistance 100 Ω, optical output power 20 μW, and peak emission wavelength 505 nm with full width at half maximum 33 mA drive current. was as compared to that sapphire. also exhibited stable operation over 500 h...

The drain-current collapse at high drain voltage has been studied in AlGaN/GaN high-electron-mobility transistors (HEMTs) on both semi-insulating (SI)–SiC and sapphire substrates using small frequency (120 Hz) sinusoidal wave superimposed dc IDS–VDS characteristics. Low collapses were observed HEMTs SI–SiC substrate when compared with the substrates. Two three thermally activated deep traps SiC-based sapphire-based HEMTs, respectively. existence of an additional trap (ΔE=0.61 eV) could be...

Systematic studies were performed on the influence of different cap layers i -GaN, n p -GaN and InGaN AlGaN/GaN high-electron-mobility transistors (HEMTs) grown sapphire by metal organic chemical vapor deposition. The decrease maximum extrinsic transconductance ( g m ) drain current density I Dmax values agrees with product two-dimensional electron gas (2DEG) mobility (µ H 2DEG sheet concentration s HEMT structures. An improved Schottky barrier height low surface roughness has been observed...

Abstract Metal–oxide–semiconductor high‐electron‐mobility transistors were demonstrated on AlGaN/GaN with electron beam (EB) evaporated ZrO 2 . The composition of the EB deposited thin films was confirmed using X‐ray photoelectron spectroscopy (XPS). fabricated ‐based MOSHEMTs exhibited high positive gate voltage operation up to +7 V low leakage current. For a comparison, conventional (HEMTs) also identical device dimensions. maximum drain current densities 1168 and 538 mA/mm observed HEMTs,...