Evolution of Pore Growth in GaAs in Transitory Anodization Regime from One Applied Voltage to Another

Abstract

The paper reports the results of investigation of the pore growth during anodic etching of (111)-oriented wafers of Si-doped n-GaAs in an environmentally friendly NaCl based electrolyte, with switching the applied voltage from a high voltage to lower one and vice-versa. Switching of the applied voltage in the process of anodization was found to cause the formation of layered porous structures with different degrees of porosity. Crystallographically oriented pores shaped as triangular prisms were produced in a stationary regime of anodization, while a more complex morphology of pores was observed at the interface between the two layers with different degrees of porosity, including pores composed of three circular ones. Based on the results of the morphology study using scanning electron microscopy, a possible mechanism of the formation of such kind of pores in the dynamic transitory regime of anodizing is discussed.