The Impact of the Surface Treatments on the Properties of Gan/3C-SiC/Si Based Schottky Barrier Diodes (original) (raw)
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Current Applied Physics, 2013
Micro-structural investigation of Ni/GaN Schottky barrier diodes has been carried out using highresolution transmission electron microscopy and electron diffraction spectrum in order to emphasize the role of Ni/GaN interface in controlling the Schottky diode behavior. Variable temperature Hall effect measurement of GaN samples along with the currentevoltage (IeV) characteristics of Ni/n-GaN Schottky barrier diodes have been measured in 100e380 K temperature range. Results are analyzed in terms of thermionic emission theory by incorporating the concept of barrier inhomogeneity at the metal/semiconductor interface. The observed anomaly of temperature dependence of Schottky barrier height and ideality factor are explained by invoking two sets of Gaussian distribution of SBH in the temperature ranges of 100e180 K and 220e380 K, respectively. The value of A** (effective Richardson constant) as determined from the modified Richardson plot is 29.2 A/(cm 2 K 2 ), which shows an excellent agreement with the theoretical value (26.4 A/(cm 2 K 2 )) in the temperature range of 220e380 K.
Ir/Pt Schottky contact oxidation for nitride-based Schottky barrier diodes
physica status solidi (c), 2007
We have fabricated Schottky diodes on GaN epitaxial wafer by using Ir/Pt Schottky contacts. After oxidation, the measured leakage current was decreased from 116 nA to 17.8 pA. In other words, the leakage current after annealing in O 2 was shown to be about four orders of magnitude smaller than that before annealing. These improvements may be attributed to IrO x formation of the metal layer, improvement of interface between the Schottky contact and the GaN layer and curing of defects due to oxidation. We also found that the Schottky barrier height and thermal stability after annealing is better than without annealing.
Cubic GaN/AlGaN Schottky-barrier devices on 3C-SiC substrates
Microelectronic Engineering, 2006
In this work, we focus on the fabrication of cubic GaN based Schottky-barrier devices (SBDs) and measured current voltage (I-V) characteristics and the critical field for electronic breakdown. Phase-pure cubic GaN and c-Al x Ga 1 À x N/GaN structures were grown by plasma assisted molecular beam epitaxy (MBE) on 200 lm thick free-standing 3C-SiC (1 0 0) substrates, which were produced by HOYA Advanced Semiconductor Technologies Co., Ltd. The thickness of the c-GaN and c-Al 0.3 Ga 0.7 N epilayers were about 600 and 30 nm, respectively. Ni/In Schottky contacts 300 lm in diameter were produced on c-GaN and c-Al 0.3 Ga 0.7 N/GaN structures by thermal evaporation using contact lithography. A clear rectifying behavior was measured in our SBDs and the I-V behavior was analyzed in detail, indicating the formation of a thin surface barrier at the Ni-GaN interface. Annealing of the Ni Schottky contacts in air at 200°C reduces the leakage current by three orders of magnitude. The doping density dependence of breakdown voltages derived from the reverse breakdown voltage characteristics of c-GaN SBDs is investigated. The experimental values of breakdown voltage in c-GaN are in good agreement with theoretical values and show the same dependence on doping level as in hexagonal GaN. From our experimental data, we extrapolate a blocking voltage of 600 V in c-GaN films with a doping level N D = 5 · 10 15 cm À3 .
Electrical characteristics of molybdenum Schottky contacts on n-type GaN
Materials Science and Engineering B Advanced Functional Solid State Materials, 2004
The Schottky barrier heights of molybdenum (Mo) on n-GaN were investigated as a function of annealing temperature by current-voltage (I-V) and capacitance-voltage (C-V) techniques. The Schottky barrier height of the as-deposited Mo/n-GaN was found to be 0.81 eV (I-V) and 1.02 eV (C-V), respectively. However, both measurements indicate that the barrier height slightly decreases upon annealing at 400 8C for 1 min in nitrogen ambient. The barrier height of Mo/n-GaN Schottky contacts at 400 8C was determined to be 0.74 and 0.92 eV, respectively. Further, an increase in annealing temperature up to 600 8C, decreased the barrier height to 0.56 and 0.73 eV. The Mo Schottky contact was also shown to be fairly stable during annealing at 400 8C.
Influence of contact shape on AlGaN/GaN Schottky diode prepared on Si with thick buffer layer
Applied Physics A, 2013
A report on the fabrication and characterization of high performance conventional and ring-shaped AlGaN/ GaN Schottky barrier diode on Si is presented. The resulting device exhibited low leakage current, which led to a detectivity performance of 3.48 × 10 13 and 1.76 × 10 13 cm Hz 1/2 W −1 , respectively, for both conventional and ring-shaped Schottky diode. The differential resistances of both devices were obtained at approximately 1.37 × 10 12 and 1.41 × 10 13 , respectively. The zero bias peak responsivities of conventional and ring-shaped Schottky diodes were estimated to be 3.18 and 2.08 A cm −2 /W, respectively. The typical UV to visible rejection ratio was observed over three orders of magnitude at zero bias. The C-V measurements was used to calculate and analyze the polarization sheet charge density of the AlGaN barrier layer by using self-consistently solving Schrodinger's and Poisson's equations. It is demonstrated that the ring shape of the Schottky barrier has higher polarization sheet charge density, which has the consequence that the Schottky shape has influence on the strain of the AlGaN barrier layer.
Barrier Height Variation in Ni-Based AlGaN/GaN Schottky Diodes
IEEE Transactions on Electron Devices, 2017
In this paper, we have investigated Ni-based AlGaN/GaN Schottky diodes comprising capping layers with silicon-technology-compatible metals such as TiN, TiW, TiWN, and combinations thereof. The observed change in Schottky barrier height of a Ni and Ni/TiW/TiWN/TiW contact can be explained by stress effects induced by the TiW/TiWN/TiW capping layer, rather than by chemical reactions at the metal-semiconductor interface. Secondary-ion mass spectroscopy and transmission electron microscopy techniques, for samples with and without a TiW/TiWN/TiW cap, have been used to show that no chemical reactions take place. In addition, electrical characterization of dedicated samples revealed that the barrier height of Ni/ TiW/TiWN/TiW contacts increases after stepwise selective removal of the TiW/TiWN/TiW cap, thus demonstrating the impact of strain.
Influence of inhomogeneous contact in electrical properties of 4H–SiC based Schottky diode
Solid-State Electronics, 2008
Schottky diodes realized on 4H-SiC n-type wafers with an epitaxial layer and a metal-oxide overlap for electric field termination were studied. The oxide was grown by plasma enhanced chemical vapor deposition (PECVD) and the Schottky barriers were formed by thermal evaporation of titanium or nickel. Diodes, with voltage breakdown as high as 700 V and ideality factor as low as 1.05, were obtained and characterized after packaging in standard commercial package (TO220).
High-Voltage Schottky Barrier Diode on Silicon Substrate
Japanese Journal of Applied Physics, 2011
New GaN Schottky barrier diodes (SBDs) on Si substrates are proposed to achieve a high-breakdown voltage. We have fabricated GaN SBDs using doped GaN/unintentionally doped (UID) GaN because doped GaN with the thickness of 200 nm is suitable for high-current operation. The 1-m-deep mesa and low-temperature annealing of ohmic contacts suppress the leakage current of GaN SBDs. Annealing of Schottky contacts also improves the interface between a Schottky contact and GaN. Annealing of ohmic contacts at 670 C yields the low leakage current of 2.8 nA through the surface and the buffer. When the anode-cathode distance is 5 m, the fabricated GaN SBD successfully achieves a low forward voltage drop of 1.3 V at 100 A/cm 2 , low on-resistance of 4.00 m cm 2 , and the low leakage current of 0.6 A/cm 2 at À100 V. The measured breakdown voltage of GaN SBDs is approximately 400 V.