Abstract:
A method for etching the InAs/InAsSbP photodiode heterostructures using a new precision etchant HBr : KMnO$_4$ 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 $\mu$m/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 $\mu$m demonstrate the minimum current density $j$ = 5.7$\cdot$10$^{-2}$ A/cm$^2$ and the typical current density $j$ = 15.5$\cdot$10$^{-2}$ A/cm$^2$. The maximum value of $R_0$ at room temperature is 1654 Ohm, while the $R_0A$ product reaches 1.17 Ohm $\cdot$ cm$^2$.
Keywords:indium arsenide, photodiode, new etchant, reverse dark currents, differential resistance.
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