title: Simultaneous four-photon luminescence, third-harmonic generation, and second-harmonic generation microscopy of GaN.
abstract: We demonstrate what is to our knowledge the first example of four-photon luminescence microscopy in GaN and apply it to quality mapping of bulk GaN. The simultaneously acquired second- and third-harmonic generation can be used to map the distribution of the piezoelectric field and the band-tail state density, respectively. Through spectrum- and power-dependent studies, the fourth power dependence of the band edge luminescence is confirmed. The superb spatial resolution of the four-photon luminescence modality is also demonstrated. This technique provides a high-resolution, noninvasive monitoring and tool for examining the physical properties of semiconductors.
authors.affiliation: Graduate Institute of Electro-Optical Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Chu
authors.forename: Ming-Che
authors.initials: MC
authors.lastname: Chan
authors.forename: Shih-Peng
authors.initials: SP
authors.lastname: Tai
authors.forename: Stacia
authors.initials: S
authors.lastname: Keller
authors.forename: Steven P
authors.initials: SP
authors.lastname: DenBaars
authors.forename: Chi-Kuang
authors.initials: CK
authors.lastname: Sun