Mechanism of low Ohmic contact resistance to p-type GaN by suppressed edge dislocations

Abstract

In this paper, an excellent Ohmic contact to p-GaN with a low specific contact resistance (ρc) of 2.0 × 10−5 Ω·cm2 is demonstrated using a patterned sapphire substrate (PSS) and oxidized Ni/Au contacts. GaN epitaxy with high crystal quality on the PSS, confirmed by high-resolution x-ray diffraction, played a key role in the improved Ohmic contact to p-GaN. The edge dislocations were annihilated during the epitaxial process on the PSS to afford a low surface dislocation density, which was in accordance with the results of transmission electron microscopy and cathodoluminescence spectroscopy. Furthermore, a reduced Fermi level and enhanced activation efficiency of Mg with suppressed segregation around the dislocations were demonstrated by Kelvin probe force microscopy and contact Hall measurements, respectively. A GaN p-channel metal oxide semiconductor device fabricated on the PSS displayed a twofold higher forward current density and superior gate controllability compared with that fabricated on a conventional sapphire substrate.

Carrier Transport Mechanism of Pt Contacts to Atomic Layer Deposited ZnO on Glass Substrates

“…4(b). Wahid et al, 40) Su et al, 43) and Puneetha et al 45) also used this method to obtain the barrier height for ohmic contacts to p-GaN. The saturation current density ranges from 5.26 mA at 298 K to 6.92 mA at 400 K. The weak temperature dependence of saturation current density is another indicator that the tunneling current is the main transport mechanism for T141 sample.…”

High-Efficiency InGaN Photo Cell Irradiated by 532 nm Laser with AlGaN Electron Blocking Layer

“…InGaN materials, dislocations widely exist in the whole material, which mainly play the role of non-radiative recombination, and has the most critical impact on the electrical properties of devices. 25,33 The edge dislocations as defects in GaN-based materials lead to poor crystal quality on the one hand. 25,26 On the other hand, they can also act as a trap in the material as a non-radiative recombination center, which leads to a reduction in effective photogenerated carrier density that affects the performance of the device.…”