Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Measurement of Second Order Susceptibilities of GaN and AlGaN



Norman Sanford, Albert Davydov, Denis V. Tsvetkov, Vladimir A. Dmitriev, Stacia Keller, Umesh Mishra, Steven P. DenBaars, S S. Park, J H. Han


Rotational Maker fringes, scaled with respect to χ11(2) of crystalline quartz, were used to determine the nonlinear optical coefficients χ31(2) and χ33(2) for samples of thin AlxGa1-xN films and a bulk free-standing GaN platelet. The AlxGa1-xN samples, ranging in thickness ranged from roughly 0.5 to 2 υ, were grown by metal-organic chemical vapor deposition (MOCVD) and hydride vapor-phase epitaxy (HVPE) on (0001) sapphire substrates. The Al mole fractions x were 0, 0.419, 0.507, 0.618, 0.660, and 0.666, for the MOCVD-grown sample, and x = 0.279, 0.363, and 0.593 for the HVPE-grown samples. The free-standing bulk GaN consisted of a 226 υ thick HVPE-grown film removed from its growth substrate. For the AlxGa1-xN samples, the magnitudes of χ31(2) and χ33(2) decreased roughly linearly with increasing x and extrapolate to 0 for x = 1 . Furthermore, the constraint expected for a perfect wurtzite structure, namely χ33(2) = -2χ31(2), was seldom observed and the samples with x = 0.660 and x = 0.666 showed χ31(2) and χ33(2) having the same sign. These results are consistent with the theoretical studies of nonlinear susceptibilities for AlN and GaN performed by Chen, et al., Appl. Phys. Lett. 66, 1129 (1995). The thicker bulk GaN sample displayed a complex superposition of high- and low-frequency Maker fringes due to the multiple-pass interference of the pump and SHG beams and the nonlinear coefficients were consistent with those measured for the thin-film GaN sample.
Journal of Applied Physics


AlGaN, GaN, III-nitrides, nonlinear optics


Sanford, N. , Davydov, A. , Tsvetkov, D. , Dmitriev, V. , Keller, S. , Mishra, U. , DenBaars, S. , Park, S. and Han, J. (2005), Measurement of Second Order Susceptibilities of GaN and AlGaN, Journal of Applied Physics, [online], (Accessed April 20, 2024)
Created February 28, 2005, Updated October 12, 2021