Cathodoluminescent Analysis of Sapphire Surface Etching Processes in a Medium-Energy Electron Beam

Abstract

Sapphire crystals are widely used in optics and optoelectronics. In this regard, it is important to study the stability of crystals under external influence and the possibility of modifying their surfaces by external influence. This work presents the results of studying the processes of the action of an electron beam with an average energy of 70 keV or less under vacuum conditions on the surfaces of sapphire substrates of various orientations. The effect of etching a sapphire surface by an electron beam in vacuum at room temperature was discovered. The highest etching rate was observed for A-plane sapphire (the average pit etching rate was 10−6 µm3/s). It was shown that the rate of etching of a sapphire surface increased many times over when gold is deposited. An in situ method for studying the process of etching a sapphire surface using cathodoluminescence analysis was considered. Possible mechanisms of sapphire etching by a beam of bombarding electrons were considered. The results obtained could be important in solving the problem of the stability of sapphire windows used in various conditions, including outer space. In addition, the proposed method of metal-stimulated etching of a sapphire surface can be widely used in patterned sapphire substrate (PSS) technology and further forming low-dislocation light-emitting structures on them.

2D-GaN/AlN Multiple Quantum Disks/Quantum Well Heterostructures for High-Power Electron-Beam Pumped UVC Emitters

“…As candidates for low-energy lines, the typical luminescence bands associated with point defects can be considered, namely, Al vacancies [V Al ] emitting at 2.7 eV [ 65 ] and their complexes with oxygen impurities [V Al -(O N ) n ] emitting in a broad band at 3.4–3.8 eV [ 66 ], substitutional carbon on the nitrogen site and a nitrogen vacancy [C N -V N ] with a prominent 2.8 eV emission peak [ 67 ], etc. In addition, CL at 330 nm might be associated with the emission of F+ centers in the c -sapphire substrate, into which a high-energy electron beam can penetrate [ 68 ].…”