Zn Mg O Homojunction-Based Ultraviolet Photodetector

• Published in: IEEE photonics technology letters 2009-07, Vol.21 (13), p.887-889
• Main Author: Shukla, G.
• Format: Article
• Language: English
• Subjects: Detectors; Optical diffraction; Optical films; Optical pulses; p-n junction; Photodiode; Photodiodes; Photonic band gap; Pulsed laser deposition; pulsed laser deposition (PLD); ultraviolet (UV) photodetector; X-ray diffraction; X-ray lasers; Zinc; Zn _{1 - {x}} Mg _{x} O
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2009.2020060

Zn 1-x Mg x O p-n photodiodes were fabricated on (0001) sapphire substrates using a pulsed laser deposition technique with different Mg contents. Ti-Au and Ni-Au metals deposited using vacuum evaporation were used as n-type and p-type contacts, respectively. The X-ray diffraction analysis showed the Zn 1-x Mg x O double layers have a single phase hexagonal wurtzite structure. The optical bandgap of Zn 1-x Mg x O films has been tuned from 3.27 to 4.26 eV by increasing the Mg content x =0.0 to x =0.34. Correspondingly, the cutoff wavelength of the resultant detectors varies from 380 to 284 nm. Zn 1-x Mg x O p-n photodiodes with different Mg contents exhibit very good performance, with a very low dark current (< 20 pA) at the bias voltage of 10 V. The ultraviolet to visible rejection ratio is more than three orders of magnitude.