Laser wavelength effect on GaN nanostructure films morphological properties deposited by PLD technique

Nanostructure thin films of gallium nitride (GaN) were prepared and deposited by using pulse laser deposition (PLD) technique at three different laser wavelengths (1064, 532 and 355 nm) to show the effect of this parameter on the films morphological properties. The Photoelectrochemical etching (PECE) technique was used to prepare porous silicon (PSi) substrates for the deposited films. With different analysis techniques that are: Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM) and Cross-Section Analysis, the properties of these films were analyzed. The AFM results showed the film deposited by laser wavelength of 1064 nm has smaller and sharper particles size with higher roughness and RMS. While, the particles size of the deposited films increases and their sharpness decreases when the laser wavelength used decreases to 532 nm and 355 nm. Furthermore, the FESEM results confirmed the formation of PSi as a result of appearance a number of pores. Also, the results appeared presence a number of prominent masses on the film surface, which increase in size as the wavelength of the laser used during the deposition process decreases. In addition, the cross-section analysis results appeared the film deposited by using laser wavelength 1064 nm is thinner compared to the films deposited using the laser wavelengths 532 nm and 355 nm. Thus, according to these results, the optimum laser wavelength to deposit GaN nanostructure thin films with high quality on PSi substrates by using PLD technique is 1064 nm. And, finally the main contributions of this research include study the effect of three different laser wavelengths during the deposition process on the morphological properties of the deposited films and use new laser wavelength (355 nm) with comparing its results with the results obtained from the deposited films by laser wavelengths 1064 nm and 532 nm to select the optimum between them.