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Qu S.,CAS Institute of Semiconductors | Wang X.,CAS Institute of Semiconductors | Wang X.,Joint Laboratory of Functional Materials and Devices for Informatics | Xiao H.,CAS Institute of Semiconductors | And 9 more authors.
EPJ Applied Physics | Year: 2014

A theoretical study of transconductance characteristics (g m-Vgs profile) of AlGaN/GaN high electron mobility transistors (HEMTs) with a graded AlGaN layer is given in this paper. The calculations were made using a self-consistent solution of the Schrödinger-Poisson equations and an AlGaN/GaN HEMTs numerical device model. Transconductance characteristics of the devices are discussed while the thickness and Al composition of the graded AlGaN layer are optimized. It is found that graded AlGaN layer structure can tailor device's gm-V gs profile by improving polar optical phonon mobility and interface roughness mobility. Good agreement is obtained between the theoretical calculations and experimental measurements over the full range of applied gate bias. © 2014 EDP Sciences.


Deng Q.,CAS Institute of Semiconductors | Wang X.,CAS Institute of Semiconductors | Wang X.,Joint Laboratory of Functional Materials and Devices for Informatics | Xiao H.,CAS Institute of Semiconductors | And 8 more authors.
Journal of Physics D: Applied Physics | Year: 2011

We employ surface topographies and phase images to investigate InN nanodots. The samples are annealed at 450, 500 and 550 □. The results reveal that the statistical distributions of number density and mean size depend on annealing ambient. The behaviours of thermal annealing between InN films and InN nanodots are distinguishable: the alloying process of InN and GaN not only occurs in InN platelets, but also in InN nanodots once the samples are annealed at the growth temperature of InN nanodots, while the main change in InN films is the decomposition of InN into In droplets and N2. © 2011 IOP Publishing Ltd.


Deng Q.-W.,CAS Institute of Semiconductors | Wang X.-L.,CAS Institute of Semiconductors | Wang X.-L.,Joint Laboratory of Functional Materials and Devices for Informatics | Yang C.-B.,CAS Institute of Semiconductors | And 9 more authors.
Chinese Physics Letters | Year: 2011

An InxGa1-xN/InN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrödinger equation according to the Kronig-Penney model. Based on particular assumptions, the power conversion efficiency is worked out. The results reveal that the In xGa1-xN/InN quantum-dot intermediate-band solar cell manifests much larger power conversion efficiency than that of p-n junction solar cells, and the power conversion efficiency strongly depends on the size of the quantum dot and the interdot distance. © 2011 Chinese Physical Society and IOP Publishing Ltd.

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