Development of a Method for Etching the InAs/InAsSbP Photodiode Heterostructures

A method for etching the InAs/InAsSbP photodiode heterostructures using a new precision etchant HBr : KMnO₄ with a low constant etching rate was proposed. The change in the ratio of the etchant components makes it possible to set the etching rate in the range of 0.1–1.6 μm/min without deterioration of the quality of the side semiconductor surface. The use of the new etchant resulted in reducing the reverse dark currents of the InAs/InAsSbP photodiodes as well as the spread of dark current value from the device to the device. Samples with a sensitive area diameter of 300 μm demonstrate the minimum current density j = 5.7 × 10^–2 A/cm² and the typical current density j = 15.5 × 10^–2 A/cm². The maximum value of R₀ at room temperature is 1654 Ohm, while the R₀A product reaches 1.17 Ohm cm².