Significant improvement in the electrical characteristics of Schottky barrier diodes on molecularly modified Gallium Nitride surfaces

Abstract

III-Nitride semiconductors face the issue of localized surface states, which causes fermi level pinning and large leakage current at the metal semiconductor interface, thereby degrading the device performance. In this work, we have demonstrated the use of a Self-Assembled Monolayer (SAM) of organic molecules to improve the electrical characteristics of Schottky barrier diodes (SBDs) on n-type Gallium Nitride (n-GaN) epitaxial films. The electrical characteristics of diodes were improved by adsorption of SAM of hydroxyl-phenyl metallated porphyrin organic molecules (Zn-TPPOH) onto the surface of n-GaN. SAM-semiconductor bonding via native oxide on the n-GaN surface was confirmed using X-ray photoelectron spectroscopy measurements. Surface morphology and surface electronic properties were characterized using atomic force microscopy and Kelvin probe force microscopy. Current-voltage characteristics of different metal (Cu, Ni) SBDs on bare n-GaN were compared with those of Cu/Zn-TPPOH/n-GaN and Ni/Zn-TPPOH/n-GaN SBDs. It was found that due to the molecular monolayer, the surface potential of n-GaN was decreased by $350 mV. This caused an increase in the Schottky barrier height of Cu and Ni SBDs from 1.13 eV to 1.38 eV and 1.07 eV to 1.22 eV, respectively. In addition to this, the reverse bias leakage current was reduced by 3-4 orders of magnitude for both Cu and Ni SBDs. Such a significant improvement in the electrical performance of the diodes can be very useful for better device functioning.

Reactively Sputtered Sb-GaN Films and its Hetero-Junction Diode: The Exploration of the n-to-p Transition

“…Coatings 2020, 10, x FOR PEER REVIEW 5 of 15 confirmation of Ga-N bond in GaN [30]. The small peak at 1,117.8 eV was contributed to the Ga-O bonding.…”

“…The XPS survey data and the XPS peaks of Ga, Sb, and N elements shown in Figure 1 were investigated with the low intensity peak of C 1s at 284.6 eV in binding energy as a reference. Figure 2b shows the high resolution XPS spectrum with strong Ga 2p1/2 and Ga 2p3/2 peaks at 1145.7 eV and 1118.81 eV, respectively, for the confirmation of Ga-N bond in GaN [30]. The small peak at 1117.8 eV was contributed to the Ga-O bonding.…”

Effect of surface passivation process for AlGaN/GaN HEMT heterostructures using phenol functionalized-porphyrin based organic molecules

“…When the molecules are adsorbed onto the surface of the semiconductor, they tune either the surface band-bending 25,26 (surface potential generated due to the surface charge) of the semiconductor or the electron affinity 27,28 or sometimes both. 29 The insertion of the organic molecules at the metalsemiconductor interfaces of Schottky contacts on some semiconductors has also been demonstrated to modify the SBH [30][31][32][33] and reduce the reverse leakage current, significantly. 33 Apart from SBH modification, the application of metal/molecular layer/semiconductor structures was also seen when organic molecules of metallated Porphyrin were used as copper metal diffusion barriers for SiO 2 -Si based CMOS technologies.…”

“…29 The insertion of the organic molecules at the metalsemiconductor interfaces of Schottky contacts on some semiconductors has also been demonstrated to modify the SBH [30][31][32][33] and reduce the reverse leakage current, significantly. 33 Apart from SBH modification, the application of metal/molecular layer/semiconductor structures was also seen when organic molecules of metallated Porphyrin were used as copper metal diffusion barriers for SiO 2 -Si based CMOS technologies. 34 Not only the gate electrode, but the application of organic molecules has also been reported to modify the source and drain electrodes on graphene based field-effect transistors.…”

Impact of Surface Chemistry and Doping Concentrations on Biofunctionalization of GaN/Ga‒In‒N Quantum Wells

“…In addition, an increase in apparent surface roughness (estimated from an effective medium approximation of the layer thickness) was observed on the APTES-treated u-GaN ( C ) and p-GaN ( A ) surfaces from ellipsometry measurements ( Table S3 ). The presence of the APTES layers can be a plausible reason for the change in surface properties between the blank and treated surfaces [ 45 ].…”