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Localized epitaxy of gallium nitride (GaN) on silicon (Si) wafers is an efficient way to relax elastically the tensile stress generated in the GaN layer after growth, allowing epitaxy of thick layers for the fabrication of vertical power devices operating at high voltage. In this study, a 4.7 μm‐thick GaN layer is grown by metal–organic vapor phase epitaxy on 200 mm‐diameter Si wafers for the fabrication of quasi‐vertical Schottky and p‐n diodes. The uniformity of the doping concentration in the layer is mapped spatially by scanning spreading resistance microscopy, while scanning capacitance microscopy illustrates the differently doped regions in the p‐n diode. The net doping concentration is extracted by capacitance–voltage (C–V) measurements and it is found to be about 3 × 1016 cm−3. On a 140 μm‐diameter quasi‐vertical p‐n diode, destructive breakdown occurs at 402 V, with no periphery protection on the device, demonstrating that localized epitaxy of GaN on Si has great potential for vertical high‐power devices. [ABSTRACT FROM AUTHOR]

Schottky barrier diodes on GaN on GaN substrates are fabricated for the purpose of material and technology characterization. The epitaxial layers are grown by MOCVD. I–V measurements as a function of the temperature in the range 80–480 K show ideality factor (n) and barrier height (ϕB) variations not following a thermionic (TE) model. Consequently, barrier height fluctuations are considered. In the temperature range 280–480 K, an average barrier height of 1.31 eV with a relatively large standard deviation (σ) of 0.15 eV is extracted using this model. The n(T) variation is also analyzed in order to extract the field sensibility of 1) the mean barrier height variation (ρ2 = −0.1) and 2) the barrier height standard deviation (ρ3 = −15 mV). The corrected Richardson plot using ϕB and σ values is linear and gives a Richardson constant of 31.5 A cm−2 K−2 close to the theoretical value of 26.4 A cm−2 K−2. For a deeper understanding of ϕB fluctuation origins, micro‐Raman mapping of the epitaxial layers and deep‐level transient spectroscopy (DLTS) are used. μ‐RS mappings show compressive strain for diodes having suffered electrical breakdown. DLTS analysis shows the presence of nine levels whose signatures are extracted and nature discussed. [ABSTRACT FROM AUTHOR]

We investigated the temperature-dependent reverse characteristics (JR-VR-T) of vertical GaN Schottky-barrier diodes with and without a fluorine-implanted edge termination (ET). To understand the device leakage mechanism, temperature-dependent characterizations were performed, and the observed reverse current was modeled through technology computer-aided design. Different levels of current were observed in both forward and reverse biases for the ET and non-ET devices, which suggested a change in the conduction mechanism for the observed leakages. The measured JR-VR-T characteristics of the non-edge-terminated device were successfully fitted in the entire temperature range with the phonon-assisted tunneling model, whereas for the edge-terminated device, the reverse characteristics were modeled by taking into account the emission of trapped electrons at a high temperature and field caused by Poole–Frenkel emission. [ABSTRACT FROM AUTHOR]

Fluorine implantation has been reported to be effective in suppressing electric fields at the edge of Schottky contacts in GaN due to the formation of fixed negative charged traps. In this study we show a detailed investigation into the behavior of fluorine implantation in GaN on material and electrical properties, and reproduce these electrical properties using TCAD simulations. A reduction in the free carrier concentration is observed by both μ-Raman, SSRM and C−V measurements, likely due to the trapping of free electrons by fluorine ions. The barrier height extracted from C-V measurements increases with increasing implant overlap area under the Schottky contact, whereas the barrier height extracted from I-V measurements remains constant. For the device without any implantation, the extracted barrier height remained the same for both extraction methods. This observation suggests the existence of a high and low double barriers originating from the implant and non-implant region respectively. TCAD simulations performed by including negative charge support the formation of a double barrier. By using the barrier height extracted from C-V measurements for the implanted region, we were able to use our TCAD model to estimate the profile of fixed negative charge, which is around 10% of the total implanted fluorine. This understanding shows that for effective design of edge terminations using fluorine implantation, consideration of the fixed negative charge as a percentage of the fluorine implantation is very important. [Display omitted] • Comprehensive Electrical and material characterization of fluorine implanted vertical GaN Schottky barrier diode performed. • Reduction of free carrier concentration in the implanted region observed through μRaman, SSRM and CV. • Presence of high barrier in the implanted region and a low barrier in the non-implanted region. • TCAD simulation suggests partial (around 10%) ionization of fluorine as negative fixed charge. [ABSTRACT FROM AUTHOR]