Nanopatterned Contacts to GaN

Abstract

The effect of nanoscale patterning using a self-organized porous anodic alumina (PAA) mask on the electrical properties of ohmic and Schottky contacts to n-GaN was investigated with the aim of evaluating this approach as a method for reducing the specific contact resistance of ohmic contacts to GaN. The electrical characteristics of contacts to these nanopatterned GaN samples were compared with contacts to planar, chemically prepared (''as-grown'') GaN samples and reactive ion etched (RIE) GaN films without any patterning. The specific contact resistivities to unintentionally doped n-GaN using a Ti/Al bilayer metallization were determined to be 7.4 · 10 )3 W cm 2 for the RIE sample and 7.0 · 10 )4 W cm 2 for the PAA patterned sample. Schottky metal contacts with Pt and Ni were prepared on the three samples to validate the effects of RIE and nanopatterning on electrical behavior. The effective barrier height was decreased and the reverse current was increased significantly in the PAA patterned sample. The radius of curvature of the nanoscale corrugation in the patterned interface was smaller than the depletion width. The reduction of the depletion width at sharp corners enhanced the local tunneling current, reducing the specific contact resistivity and decreasing the effective barrier height. These results suggest that nanopatterning with PAA on GaN can significantly lower the contact resistance.

Enhancement of electric field properties of Pt/nanoplatelet MoO3/SiC Schottky diode

“…Since the first report of the hydrogen sensitive Pd/metal oxide contacts [37] there have been numerous reviews reporting the electrical characteristics of thin film based Schottky diodes in application to gas sensing [29,38]. With the development of nanostructured films, there have only been several reviews to date that have shown the Schottky diode characteristics of nanocontacts [1,19,[39][40][41][42][43][44][45][46] and only recently have there been reviews for Schottky nanocontact based gas sensors [30,[47][48][49][50][51][52][53][54][55].…”

Numerical study of reduced contact resistance via nanoscale topography at metal/semiconductor interfaces

“…However, Fermi level pinning [3] and limitations in doping concentration due to solid solubility limits can inhibit the reduction of ρ c , or specific contact resistance, which relates contact area to resistance. An alternate approach to reducing ρ c has been shown for lightly doped n-GaN [4]. In this study, nanoscale features were intentionally etched into the semiconductor surface, using a porous alumina etch mask, creating an array of pits prior to metal deposition.…”

Controlled Growth of Ordered Nanopore Arrays in GaN

“…9,10 The III-nitrides are interesting materials for nanopore applications as they are mechanically robust and biologically compatible, as well as electrically and optically active. 11 Nanopore structures have been previously fabricated within GaN by reactive ion etching (RIE) 12 and inductively coupled plasma (ICP) etching, [13][14][15] anodization and wet chemical etching, 16,17 and growth of porous particles and nanowires. 18,19 Direct RIE and ICP etching of nanopores results in damaged surfaces, thus degrading the quality of electrically active interfaces.…”