Limitation des performances des photodétecteurs à avalanche GaAIAsSb par effet tunnel

The design and performance characteristics of experimental GaAlAsSb mesa diodes for use as avalanche photodetectors are described. The 5-8 microns thick GaAlAsSb thin films were deposited on (111)-oriented GaSb substrates by liquid phase epitaxy, thereby obtaining a transition band energy of 0.915 eV. The diode formed was 140 microns in diameter and featured a TiAu electrode formed on the surface by RF cathodic vaporization. The results of electrical tests to determine the capacitance-voltage, current-voltage and spectral characteristics of the diodes are provided, along with data on the dark current noise due to granulation in the materials. The dark current, caused by either band-to-band tunneling or defect-assisted tunneling, limits the potential value of the multiplicative factor while increasing the noise-equivalent power. Improving the material properties, i.e., eliminating the tunneling effect, requires lowering the residual carrier concentration, a difficult task when working with GaSb materials.