Micro-structural and temperature dependent electrical characterization of Ni/GaN Schottky barrier diodes

• A detailed micro-structural analysis of the Ni/n-GaN Schottky contacts using HRTEM.
• Variable temperature Hall experiments have given an insight on the origin of barrier inhomogeneity observed.
• I–V–T of high quality diodes (10−8 mbarr vacuum deposited) at various temperatures.
• The results analyzed by thermionic emission theory by incorporating the concept of barrier inhomogeneity at interface.
• Value of A** (Richardson constant) 29.2 A/(cm2 K2) is found close to theoretical value 26.4 A/(cm2 K2).

Micro-structural investigation of Ni/GaN Schottky barrier diodes has been carried out using high-resolution transmission electron microscopy and electron diffraction spectrum in order to emphasize the role of Ni/GaN interface in controlling the Schottky diode behavior. Variable temperature Hall effect measurement of GaN samples along with the current–voltage (I–V) characteristics of Ni/n-GaN Schottky barrier diodes have been measured in 100–380 K temperature range. Results are analyzed in terms of thermionic emission theory by incorporating the concept of barrier inhomogeneity at the metal/semiconductor interface. The observed anomaly of temperature dependence of Schottky barrier height and ideality factor are explained by invoking two sets of Gaussian distribution of SBH in the temperature ranges of 100–180 K and 220–380 K, respectively. The value of A** (effective Richardson constant) as determined from the modified Richardson plot is 29.2 A/(cm2 K2), which shows an excellent agreement with the theoretical value (26.4 A/(cm2 K2)) in the temperature range of 220–380 K.