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Contact Resistivity (contact + resistivity)

Distribution by Scientific Domains

Physics and Astronomy	100%

Selected Abstracts

Transparent Ohmic Contacts on p-GaN Using an Indium Tin Oxide Overlayer

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003
Soo Young Kim
Abstract We report a low-resistant, thermally stable ohmic contact on p-GaN using a promising contact scheme of Ni/Au/ITO. Ni/Au contact on p-GaN was annealed at 500 °C under an oxidizing atmosphere before ITO deposition, forming a NiO layer acting as a diffusion barrier of In atoms from ITO. Specific contact resistivity as low as 4.8 × 10,4 ,cm2 was obtained from the Ni (20 Å)/Au (30 Å)/ITO (1000 Å) contact annealed at 500 °C under an oxidizing atmosphere. Contact resistivity is decreased due to crystallization of ITO and Au indiffusion through the NiO layer after annealing at 500 °C under an oxidizing ambient. Also, under this condition, the measured optical transmittance of Ni/Au/ITO was above 80% at a wavelength of 470 nm. [source]

Implementation of the GaN lateral polarity junction in a MESFET utilizing polar doping selectivity

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2010
Ramón Collazo
Abstract The difference in surface energies between the Ga-polar orientation and the N-polar orientation of GaN translates into a completely different behavior for the incorporation of intentional and unintentional impurities. Oxygen is found to be an impurity with higher concentration in the N-polar films than in Ga-polar films and is the cause of n-type conductivity observed in N-polar films. Utilizing this doping selectivity we fabricated a depletion-mode metal-semiconductor field effect transistor (MESFET) with n-type N-polar domains as source and drain and a Ga-polar channel on polarity-patterned wafers. The difference in the electronic properties of the different domains, i.e., as-grown N-polar domains are n-type conductive and Ga-polar domains are insulating, allows for laterally selective doped areas that can be realized for improving contact resistance to the n-type conduction channel. Basically, the N-polar domains acted as the ohmic contacts to the channel localized in a Ga-polar domain. A MESFET with a Schottky gate was fabricated as an example of implementation of this novel structure showing a lowering in the specific contact resistivity. [source]

Selective-area growth and fabrication of recessed-gate GaN MESFET using plasma-assisted molecular beam epitaxy

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
Seung Jae Hong
Abstract For the first time, selective-area growth (SAG) technique has been developed using plasma-assisted molecular beam epitaxy (PAMBE), enabling fabrication of a recessed-gate structure for the metal-semiconductor field-effect transistor (MESFET) without etching. On patterned SiO2 samples, polycrystalline GaN and single crystal n+ -GaN were observed to grow in the masked and unmasked regions, respectively. The regrown layers were analyzed using AFM. Ohmic contact formed on the n+ -GaN exhibited a vastly improved contact resistivity of 1.8 × 10,8 , cm2, giving rise to excellent device characteristics including a peak drain current of 360 mA/mm and a maximum transconductance of 46 mS/mm. The advantages of SAG were further investigated by comparing the dc characteristics of recessed-gate and unrecessed MESFET. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Mg-doped AlGaN grown on an AlN/sapphire template by metalorganic chemical vapour deposition

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006
Hongbo Yu
Abstract The growth of high-performance Mg-doped p-type AlxGa1,xN (x = 0.35) layers using low-pressure metalorganic chemical vapour deposition on an AlN/sapphire template is reported. The influence of growth conditions on the p-type conductivity of the AlxGa1,xN (x = 0.35) alloy was investigated. It was found that the p-type resistivity of the AlGaN alloy demonstrates a marked dependence on the Mg concentration, V/III ratio and group III element flow rate. A minimum p-type resistivity of 3.5 , cm for AlxGa1,xN (x = 0.35) epilayers was achieved. A Ni/Au (10 nm/100 nm) ohmic contact was also fabricated and a specific contact resistivity of 8.1 × 10,2 , cm2 was measured. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Vertical-type InGaN/GaN light emitting diodes with high efficiency reflector ITO/APC alloy on p-GaN

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010
Sung Min Hwang
Abstract We demostrate the efficient p-type reflector for high performance vertical InGaN/GaN light emitting diodes (LEDs) with 1 × 1mm2 chip size. The reflector consists of Indium-Tin-Oxide (ITO) and Ag-Pd-Cu (APC) alloy. The ITO was inserted between p-GaN layer and APC alloy using RF magnetron sputtering to prevent inter-diffusion of APC into GaN layer. Transmission electron microscopy (TEM) result shows that ITO plays an impotant role as a diffusion barrier to APC alloy. In addition, the contact resistivity of ITO to p-GaN layer was measured to be 1.32 × 10 -3 ,cm2 at annealing temperature of 600 °C for 1 minute. APC alloy was adpoted to acheive a higher reflectance for improvement of a light extraction efficiency. The APC alloy reflector appeared to have a higher reflectivity compared to conventional Ni/Ag film reflector. The verical LEDs with ITO/APC alloy reflectors showed the light-output power of 295 mW at an injection current of 350 mA, which is 15% higher than that with Ni/Ag reflectors. The output power enhancement is attributed to the increase of light extraction efficiency due to high reflectivity of APC alloy (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]