Title :
Raman spectroscopy study on free-standing GaN separated from sapphire substrates by 532 nm Nd:YAG laser lift-off
Author :
Ho, H.P. ; Lo, K.C. ; Siu, G.G. ; Surya, C.
Author_Institution :
Dept. of Phys. & Mater. Sci., City Univ. of Hong Kong, Kowloon, China
Abstract :
Gallium nitride (GaN) thin films grown on sapphire substrates were successfully lifted onto silicon wafers using a laser lift-off (LLO) process induced by a 532 nm, Nd:YAG pulsed laser. Although the photon energy (2.33 eV) is much lower than the band gap of hexagonal GaN (3.41 eV), free-carriers absorption can heat up and consequently causes detachment of the GaN film from the sapphire substrate. Raman measurement conducted before and after LLO showed that the surface structure of the lifted GaN changed from hexagonal to a cubic structure.
Keywords :
Raman spectra; absorption; energy gap; gallium compounds; laser materials processing; pyrolysis; scanning electron microscopy; semiconductor technology; semiconductor thin films; surface structure; wide band gap semiconductors; 2.33 eV; 3.41 eV; 532 nm; GaN film detachment; GaN-Al2O3; GaN-Si; LLO; Nd:YAG laser lift-off; Nd:YAG pulsed laser; Raman spectroscopy; SEM; YAG:Nd; YAl5O12:Nd; cubic structure; free-carriers absorption heat production; gallium nitride thin films; hexagonal GaN band gap; hexagonal surface structure; photon energy; sapphire substrates; silicon wafers; thermal decomposition; Absorption; Gallium nitride; III-V semiconductor materials; Optical pulses; Photonic band gap; Raman scattering; Semiconductor thin films; Silicon; Spectroscopy; Substrates;
Conference_Titel :
Electron Devices Meeting, 2002. Proceedings. 2002 IEEE Hong Kong
Print_ISBN :
0-7803-7429-0
DOI :
10.1109/HKEDM.2002.1029169
