A cadmium sulfide thin film deposited by a chemical bath deposition technique has been found to act as a passivating layer and a capping layer for GaSb photodiodes. X-ray photoelectron spectroscopy analysis shows the presence of Ga–S and Sb–S bonds along with the cadmium binding energies. Reduction in the reverse leakage current after the passivation is accompanied by a significant increase in the zero bias resistance-area product (14.29–100Ωcm2). In addition, the dependence of the zero bias resistance-area product on the device dimension reduced considerably. There was no degradation in the dark current performance over a period of 3months, indicating long-term stability.

The evolution of the dominant carrier transport mechanism of Alx Ga1‐xN/GaN Schottky barrier diodes with increasing Al mole fraction x (x = 0.2, 0.3, 0.4, and 0.5) is investigated. The Schottky barrier height (SBH) linearly increases with the work function of Schottky metal with the slope factor of ∼0.5 irrespective of x. The SBH, the ideality factor, and the reverse leakage current, however, show an increasing deviation from the predicted values given by the thermionic‐emission theory as x increases. The XPS analysis reveals enhanced predominant incorporation of oxygen donors and an increase in the energy band bending at the surface of AlGaN with increasing x, indicating that the carrier transport by tunnelling through the thin, heavily doped Schottky barrier becomes dominant. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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