Using a generalized extraction method, the fixed charge density Nint at the interface between in situ deposited SiN and 5 nm thick AlGaN barrier is evaluated by measurements of threshold voltage Vth of an AlGaN/GaN metal insulator semiconductor high electron mobility transistor as a function of SiN thickness. The thickness of the originally deposited 50 nm thick SiN layer is reduced by dry etching. The extracted Nint is in the order of the AlGaN polarization charge density. The total removal of the in situ SiN cap leads to a complete depletion of the channel region resulting in Vth = +1 V. Fabrication of a gate stack with Al2O3 as a second cap layer, deposited on top of the in situ SiN, is not introducing additional fixed charges at the SiN/Al2O3 interface.

Random telegraph signal (RTS) fluctuations with relative amplitude up to 50% are observed in forward and reverse gate current of unstressed and reverse-bias-stressed AlGaN/GaN high electron mobility transistors. Measurements of RTS amplitude and mean pulse widths as a function of forward gate bias indicate that the RTS is due to modulation of current along an intrinsic or stress-induced percolation path across the AlGaN-barrier by electron capture and emission on a trap within the barrier. Processes of electron capture from GaN to trap and subsequent tunneling to metal gate or electron exchange between GaN channel and the trap are considered. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3701164

No abstract

We experimentally prove the viability of the concept of the double-heterostructure quantum well InAlN/GaN high-electron-mobility transistor (HEMT) for the device higher robustness and reliability. In the single quantum well InAlN/GaN HEMTs, the intrinsic channel resistance increases by 300% after 1 h off-state stress; much less degradation is observed in the double-heterostructure device with an AlGaN back barrier. Physicsbased device simulation proves that the back barrier blocks the rate of carrier injection into the device buffer. However, whatever the quantum well design is, the energy of the injected electrons in the buffer of InAlN/GaN-based HEMTs is higher than that in the buffer of AlGaN/GaN HEMTs. This energy may be sufficient for releasing hydrogen from GaN point defects.

No abstract

No abstract

No abstract

No abstract