Fabrication of black GaAs by maskless inductively coupled plasma etching in Cl2/BCl3/O2/Ar chemistry

Abstract

Textured GaAs surfaces with near-zero reflectance are promising for the antireflective application of photovoltaic and optoelectronic devices. Such surfaces can be described as “black GaAs” attributing to their superior light-trapping capability. In this paper, black GaAs with grasslike nanowire bunches was fabricated in a maskless inductively coupled plasma (ICP) etching manner. Cl2/BCl3/O2/Ar chemistry was selected as the feed gas in the ICP system. Undoped black GaAs with solar-weighted reflectance (SWR) of 1.01% and doped black GaAs with SWR of 2.56% were obtained. In the study, the surface morphology and antireflection behavior of the textured GaAs were found to vary at different etching time, power conditions, and O2 contents. Combined with the surface element analyses, the etching mechanism of the maskless process was proposed. It is considered as a competing mechanism for the removal of the GaAs material by Cl-based gases and the passivation of the surface by O radicals. This maskless texturing method has the advantages of simplicity, scalability, and efficiency. The black GaAs of such patterns has prospects in photodetectors, solar cells, and flexible devices.