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High responsivity A-plane GaN-based metal-semiconductor-metal photodetectors for polarization-sensitive applications

2009-05-25
Navarro, A.
Rivera, C.
Pereiro, J.
Munoz, E.
İmer, Muhsine Bilge
DenBaars, S. P.
Speck, J. S.
The fabrication and characterization of metal-semiconductor-metal polarization-sensitive photodetectors based on A-plane GaN grown on R-plane sapphire substrates is reported. These photodetectors take advantage of the in-plane crystal anisotropy, which results in linear dichroism near the band gap energy. The high resistivity of the A-plane GaN material leads to extremely low dark currents. For an optimized finger spacing of 1 mu m, dark current density and responsivity at 30 V are 0.3 nA/mm(2) and 2 A/W, respectively. A maximum polarization sensitivity ratio of 1.8 was determined. In a differential configuration, the full width at half maximum of the polarization-sensitive region is 8.5 nm.