[en] We fabricated hybrid structures using combined properties of organic and inorganic materials for application in light emitting diode. The hybrid structures were demonstrated using poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as organic materials and n-GaN as inorganic materials. To investigate the effects of organic layer thickness, we changed polymer concentration and spin speed of MDMO-PPV solution. We obtained current rectifying behaviour with MDMO-PPV layer of approximate 60 nm thickness. The hybrid structure shows broad emissions covering orange range in both photoluminescence and electroluminescence spectra and its band structures matched well with energy band gap of GaN and MDOM-PPV. We expect the potential applications and the enhanced efficiency in optoelectronic devices with hybrid structure by making progress the results. -- Highlights: • We fabricated the hybrid structures using MDMO-PPV, PEDOT:PSS and n-GaN. • We investigated the effects of organic layer thickness in hybrid devices. • These results will provide a guide to develop the hybrid optoelectronic devices

[en] The growth condition of thin heavily Mg-doped GaN capping layer and its effect on ohmic contact formation of p-type GaN were investigated. It is confirmed that the excessive Mg doping can effectively enhance the Ni/Au contact to p-GaN after annealing at 550 °C. When the flow rate ratio between Mg and Ga gas sources is 6.4% and the layer width is 25 nm, the capping layer grown at 850 °C exhibits the best ohmic contact properties with respect to the specific contact resistivity (ρ_c). This temperature is much lower than the conventional growth temperature of Mg-doped GaN, suggesting that the deep-level-defect induced band may play an important role in the conduction of capping layer. (paper)

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[en] Recent success with the fabrication of high-performance GaN-on-Si high-voltage HFETs has made this technology a contender for power electronic applications. This paper discusses the properties of GaN that make it an attractive alternative to established silicon and emerging SiC power devices. Progress in development of vertical power devices from bulk GaN is reviewed followed by analysis of the prospects for GaN-on-Si HFET structures. Challenges and innovative solutions to creating enhancement-mode power switches are reviewed. (invited review)

[en] Based on the principle of charge neutrality and fact that 2DEG electrons come from the surface donor states (SDSs) of AlGaN, a method for analytical calculation of the bare surface barrier height $({\mathrm{\varphi <!--\; ??\; -->}}_B)$ and 2DEG density (N _S) of AlGaN/GaN heterostructure exerted uniaxial stress is presented, and mechanism of their changes dependent on SDSs is illustrated. Two general cases of the uniform distributed SDSs (UD-SDSs) and high-density-single-level SDSs (HDSL-SDSs) are considered in the analytical calculation and the results are consistent with the 3D electro-mechanical simulation and experimental data. The uniaxial stress changes the piezoelectric polarization charge in the AlGaN/GaN heterostructure, correspondingly, for the case of UD-SDSs, ${\mathrm{\varphi <!--\; ??\; -->}}_B$ and N _S have changes which are dependent on the density of UD-SDSs, while for HDSL-SDSs, ${\mathrm{\varphi <!--\; ??\; -->}}_B$ is fixed (Fermi-level pinning) and N _S has a maximum change. (paper)

[en] It has been clarified that several peculiarities of I-V characteristics at U < 1.5 V and low frequency noise dependences in InGaN/GaN nanostructures for green and blue spectral range as well as in Schottky barriers in AlGaN/GaN HEMT nanostructures are evoked by the non-radiative coupled deep donor-acceptor pair recombination. The strong contribution of the non-radiative donor-acceptor recombination in the degradation of the nanostructures properties has been confirmed experimentally. (paper)

[en] Anisotropic, smooth etching of the group-III nitrides has been reported at relatively high rates in high-density plasma etch systems. However, such etch results are often obtained under high de-bias and/or high plasma flux conditions where plasma induced damage can be significant. Despite the fact that the group-III nitrides have higher bonding energies than more conventional III-V compounds, plasma-induced etch damage is still a concern. Attempts to minimize such damage by reducing the ion energy or increasing the chemical activity in the plasma often result in a loss of etch rate or anisotropy which significantly limits critical dimensions and reduces the utility of the process for device applications requiring vertical etch profiles. It is therefore necessary to develop plasma etch processes which couple anisotropy for critical dimension and sidewall profile control and high etch rates with low-damage for optimum device performance. In this study we report changes in sheet resistance and contact resistance for n- and p-type GaN samples exposed to an Ar inductively coupled plasma (ICP). In general, plasma-induced damage was more sensitive to ion bombardment energies as compared to plasma flux. In addition, p-GaN was typically more sensitive to plasma-induced damage as compared to n-GaN

[en] In this paper, we report the recent progress in the high-frequency performance of enhancement-mode devices in the novel N-polar GaN technology and provide a pathway for further scaling. The intrinsic advantages of electron confinement, polarization doping of the back-barrier and the absence of a source barrier in N-polar GaN technology were leveraged with polarization engineering with a top barrier for enhancement mode operation and advanced self-aligned source/drain technology for low parasitic access resistances. The scalability of the device structures are explored in terms of short-channel effects and high-frequency performance. Low-field electron mobility in vertically scaled channel was also investigated providing insights on the scattering mechanism. (invited review)

[en] GaN, a wide bandgap semiconductor successfully implemented in optical and high-speed electronic devices, has gained momentum in recent years for power electronics applications. Along with rapid progress in material and device processing technologies, high-voltage transistors over 600 V have been reported by a number of teams worldwide. These advances make GaN highly attractive for the growing market of electrified vehicles, which currently employ bipolar silicon devices in the 600–1200 V class for the traction inverter. However, to capture this billion-dollar power market, GaN has to compete with existing IGBT products and deliver higher performance at comparable or lower cost. This paper reviews key achievements made by the GaN semiconductor industry, requirements of the automotive electric drive system and remaining challenges for GaN power devices to fit in the inverter application of hybrid vehicles. (invited review)