NiAl/n-GaAs Schottky diodes: Barrier height enhancement by high-temperature annealing

Abstract

A metallurgically stable and laterally uniform contact to n-GaAs with an enhanced barrier height (0.99 V) and an ideality factor of 1.10 has been achieved with a NiAl bimetallic metallization. This barrier height, as measured by the forward current-voltage technique after annealing for 20 s at 650 °C, is higher than the reported barrier heights of refractory metallizations to n-GaAs. Auger electron spectroscopy (AES) sputter profiles reveal an Al-Ga exchange reaction after high-temperature (500–950 °C) rapid thermal annealing. From these results, the barrier height enhancement is attributed to the formation of an Al1−xGaxAs layer at the NiAl/n-GaAs interface. The thermal stability and low electrical resistivity of the NiAl phase, the enhanced barrier height on n-GaAs, and the ease of patterning the as-deposited Ni/Al/Ni layered structure by lift-off techniques make NiAl a very promising gate contact material for GaAs metal-semiconductor field-effect transistors and related devices.

Effects of swift heavy ion irradiation on the electrical characteristics of Au/n-GaAs Schottky diodes

“…Any mechanism that modifies the properties of the interface such as the introduction of an interfacial layer [1][2][3][4], annealing [5,6], irradiation with gamma rays [7,8], protons [9][10][11][12][13][14] and neutrons [14][15][16], ion implantation, [17][18][19] and high-energy ion beam irradiation [20][21][22][23][24][25][26] are found to alter the characteristics of the barrier. The Schottky barrier height (SBH) forms a very important parameter of the diode as it controls the electrical transport across the barrier.…”

Metallurgical and Electrical Characteristics of MoAlx Schottky Contacts to n-GaAs

“…The enhancement of the barrier height after high temperature annealing has also been observed for Al/n-GaAs [8] and NiAl/n-GaAs [9]. It is believed that the barrier height enhancement of MoAlx/n-GaAs can be attributed to the formation of an AlxGal-xAs layer at the interface.…”

PtIn2 ohmic contacts to n-GaAs via an In-Ga exchange mechanism

“…The exchange mechanism was first hypothesized by Sands et al, 10 who noted Schottky barrier enhancement of Ni/Al/Ni/n-GaAs contacts after high temperature heat treatment. They attributed this change in electrical properties to the formation of Al x Ga 1Ϫx As at the contact interface through the exchange of Al and Ga atoms between the NiAl metallization and the GaAs substrate.…”