Single-wire photodetectors based on InGaN/GaN radial quantum wells in GaN wires grown by catalyst-free metal-organic vapor phase epitaxy

We present a letter on single-wire photodetectors based on radial n-i-n multiquantum well (QW) junctions. The devices are realized from GaN wires grown by catalyst-free metalorganic vapor phase epitaxy coated at their top by five nonpolar In0.16Ga0.84N/GaN undoped radial QWs, and are sensitive to light with energy E>2.6 eV. Their photoconductive gain is as high as 2×103. The scanning photocurrent microscopy maps evidence that the detector response is localized at the extremity containing the QWs for both below (at λ=488 nm) and above GaN band gap (at λ=244 nm) excitation. This confirms that the device operates as a radial n-i-n junction.