Structure and composition of thin GaAs1-x-yNxBiy films produced by pulsed laser deposition

Abstract

Uniaxial cold pressing was used to fabricate GaAs0,9Bi0,1 targets with 10% Bi content. Thin films of GaAs1-x-yNxBiy onto a GaAs (100) substrate were obtained from the formed GaAs0,9Bi0,1 target by pulsed laser deposition in an argon-nitrogen gas atmosphere, and their structure and composition were studied. It is shown that on the surface of the film there are predominantly small microdroplets with a diameter of less than 0,5 μm, formed by Bi atoms. Large microdroplets with a diameter of 2 to 6 μm consist partly of Bi and Ga. No microdroplets formed only from Ga were found. It is noted that small Ga microdroplets are adsorbed on the surface of large Bi microdroplets without forming a GaBi alloy. It was also found that the formation of Bi microdroplets also occurs due to the segregation of Bi atoms on the film surface. The energy-dispersive spectroscopy data make it possible to characterize the resulting thin films as GaAs0,995N0,015Bi0,03. The mean square roughness of the film surface was 12,2 nm. The resulting GaAs0,995N0,015Bi0,03 film has a polycrystalline structure. An analysis of the X-ray diffraction data showed that the film grew according to the Volmer-Weber law, when islands are nucleated and their sizes subsequently increase. The nuclei are most likely formed by GaAs, GaN, GaAsN, GaAsBi, and GaAsNBi. The calculated full width at half height for GaAs0,995N0,015Bi0,03 was –0,8656ʺ, and the average crystallite size was 1,6 nm.

Keywords

• thin films
• iii-v-n-bi
• gaas1-x-ynxbiy
• pulsed laser deposition
• diluted nitrides
• diluted bismuthides