Gan-based Schottky diodes

Abstract

In this chapter, the fundamental theory, preparation, characterization and application of Schottky diodes on Gallium Nitride (GaN) will be presented, including: (1) Basic concepts of Schottky contact on GaN; (2) Fundamental fabrication process, including surface treatment, dry etching, device isolation, ohmic contact, Schottky contact process and interconnection; (3) Characterization of Schottky diodes on n-GaN with NiAu and Cu contact metals, including current-voltage and capacitance-voltage methods. Comparing with the commonly-used NiAu contact, Cu Schottky metal has the advantage of low metal resistance and low cost. The reverse leakage current density of Cu Schottky diode on n-GaN is lower than that of Ni/Au contact. The Schottky barrier height of Cu contact is found to be about 0.1 eV higher than that of Ni/Au contact; (4) A new capacitance-voltage method was developed to extrapolate the Schottky barrier height on n-GaN with exponential carrier concentration profile; (5) For thermal stability or hightemperature operation, Schottky contacts utilizing refractory metal nitrides on n-GaN, such as ZrN and MoN, will be evaluated. Their performances and the performances after high-temperature treatment will also be reported; (6) Evaluation of Schottky diodes based on AlGaN/GaN heterostructure will be presented; (7) GaN Schottky diodes for microwave rectification and power electronics will be evaluated; (8) Finally, we will present a five-stage monolithic Cockcroft-Walton voltage multiplier with metal-insulatormetal capacitors and Schottky diodes based on AlGaN/GaN HFET structure, by which voltage multiplication of two times to the input peak-to-peak voltage was obtained. © 2009 by Nova Science Publishers, Inc. All rights reserved.