Temperature-dependent I-V characteristics and photoresponse of GaSb Schottky diodes

Abstract

In this work, current–voltage I-V characteristics of the Au/n-GaSb Schottky diodes were measured at temperatures in the wide range of 80-340 K to identify current transport mechanism. Measured I-V curves were analyzed under the assumption that the total current is expressed as sum of components of each current transport mechanism. First, I-V curves were fitted under the assumption that total current composed of the thermionic emission current and the secondary current component regarded as tunneling current or Shockley–Read–Hall recombination current. Fitted values are perfectly matched with the measured currents and proportion of the thermionic emission current decreased as the temperature lowered. We also extracted diode parameters from TE current, and the obtained barrier heights and ideality factors were strongly temperature dependent. This anomaly was successfully explained by Werner’s barrier inhomogeneity theory. And the mean barrier height and standard deviation of the diode were obtained as 0.70 V and 0.087 V. The secondary current coefficients were compared with the thermionic field emission tunneling coefficient and the value of 2kT which is a coefficient correspond to the Shockley-Read–Hall recombination current. In the secondary current, tunneling was dominant at the low temperature and Shockley-Read-Hall recombination current became dominant at the temperature higher than 220 K. Other current components such as leakage current, Auger and radiative recombination currents are also considered and it was shown that they are marginal components. And for the photoresponse analysis, GaSb Schottky photodiodes were fabricated by depositing Schottky metal 5 nm and forming an optical window by the lift-off process. Photocurrent was measured at room temperature and low temperature under the light illummination. Photodiodes have shown uniform external quantum efficiency (EQE) over a wide spectral range from UV to SWIR wavelengths.