Electrical and Optical Characteristics of <I>n</I>-ZnO/<I>p</I>-GaN Hetero-Junction Diode Fabricated by Ultra-High Vacuum Sputter

Abstract

We investigated the electrical and optical properties of n-ZnO/p-GaN hetero-junction diode fabricated by an ultra-high vacuum radio frequency magnetron sputter. A physical relationship between the rotation rate during deposition process and post annealing conditions after deposited ZnO layer on p-GaN layer was discussed. When the rotation rates during deposition process of n-ZnO layer were 5 rpm and 15 rpm, the full width at half maximum of photoluminescence spectra of ZnO layer on the p-GaN layer was about 106 and 133 meV, respectively. Also, the ratio of deep level emission to near band edge emission was dramatically increased as increasing the rotation rate from 5 to 15 rpm. The n-ZnO/p-GaN hetero-junction diode grown at 5 rpm has a higher ratio of forward to reverse currents than the diode grown at 15 rpm. Also, the 600 degrees C-annealed diodes with 5 rpm showed good rectifying behavior with the barrier height of 0.74 eV, the ideality factor of 12.2, and the forward to reverse current ratio of 614 at +/- 8 V.

Ultraviolet electroluminescence with electrically tunable colour from epitaxial n-(0001)ZnO/p-(0001)GaN light-emitting diodes

“…It is noticeable that the value of the non-ideality factor is found to be quite high in all cases. Note that high η values have often been reported for heterostructure devices [6,11,27,28] and attributed to barrier inhomogeneity, interface states, leakage due to tunnelling and non-uniform distribution of carriers at the interface [29,30]. Since all of our samples exhibit good epitaxial and interface qualities, it is unlikely that above factors are responsible for the high values of η obtained here.…”

“…Many groups have reported the * Author to whom any correspondence should be addressed. fabrication of n-ZnO/p-GaN junction based LEDs, where various growth techniques, such as molecular beam epitaxy [3], metalorganic chemical vapour deposition [4], chemical bath deposition [5], RF magnetron sputter [6] and pulsed laser deposition (PLD) [7], are used to grow the ZnO layer. Emission of light in the wavelength range of 390-415 nm has also been observed from these devices [5,[8][9][10].…”