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The amorphous oxide thin-film transistor (TFT)-oriented simulator [subgap Density of states (DOS)-based Amorphous Oxide TFT Simulator (DeAOTS)] is proposed, implemented, and demonstrated for amorphous indium–gallium–zinc–oxide (a-IGZO) TFTs. It only consists of parameters having their physical meanings and is supplied with concrete techniques for parameter extraction. Among the physical parameters, the acceptor-like DOS gA(E) was experimentally extracted using the multifrequency C–V technique, whereas the donor-like DOS gD(E) and the doping concentration ND were extracted using numerical iterations. The simulation result reproduces the DOS and thin-film-thickness-dependence of dc I–V characteristics very well. Compared with the previously reported a-Si TFT models, the proposed DeAOTS model not only reflects the strong VGS dependence of the effective mobility (\mueff) but also clarifies the relations between process-controlled DOS parameters and dc I– V characteristics based on experimentally extracted DOS parameters. Also, it sufficiently takes into account the peculiar situation of amorphous oxide TFTs where the free-carrier charge can be larger than the localized one out of the total induced charge. Moreover, it reproduces the measured electrical characteristics within the wide range of VGS/V \rm DS with a single equation, not distinguishing the operation regions such as the subthreshold, linear, and saturation regimes. [ABSTRACT FROM PUBLISHER]

We report the effect of V-shaped pit size, inverted hexagonal pits embedded in InGaN multiple quantum well, on the reverse leakage current of InGaN light-emitting diodes (LEDs). It was found that the reverse leakage current of InGaN LEDs with larger V-shaped pits is significantly reduced from 1.80 mA down to 3.84 nA at -30~V by several orders of magnitude. We claim that this improvement is accounted for increased Poole-Frenkel barrier height of carrier trapped at the deep centers via enlarged V-pit formation, consequently resulting in lower reverse current of InGaN LEDs. [ABSTRACT FROM AUTHOR]

We investigate the reverse leakage characteristics of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) grown on Si (111) substrate by metal–organic chemical vapor deposition. The reverse leakage characteristics of InGaN/GaN LED on silicon are measured as low as \sim10 nA at -5 V and -10 \mu\A at -15 V. Temperature-dependent current–voltage ( I–V) measurements of LED devices reveal that the reverse leakage current mechanism is mainly attributed to the field-enhanced thermionic emission, also known as Poole–Frenkel emission, of carriers from deep centers within the space charge region up to \sim-18 V. The analysis of T–I –V curve yields the calculation of the coefficient of the Poole–Frenkel effect (\1.12 \times \10^-4\ \eV\cdot \V^-1/2\cdot\cm^1/2) and activation energies of carriers ( \sim214 meV at -5 V). With further increase of reverse bias, up to - 40 V, LED devices exhibit the onset of space-charge-limited leakage current mechanism without any local breakdown. [ABSTRACT FROM AUTHOR]