Effect of oxygen plasma modification on Pd/Al/Au Ohmic contacts on undoped AlN

Abstract

The influence of surface modification of undoped AlN by oxygen plasma on the Pd/Al/ Au Ohmic contacts was studied. Pd/Al/Au alloys were deposited on undoped AlN films by electron beam evaporation and annealed from 750 °C to 900 °C for 30 s to form metalsemiconductor contacts. All the samples without oxygen plasma treatment were Schottky contacts. After oxygen plasma treatment, the contacts below annealing temperature of 850 °C were Schottky type. However, the contacts changed to be Ohmic type with specific contact resistivity of 3.01 Ω • cm 2 when the annealing temperature was 900 °C. The samples were characterized by scanning electron microscopy and x-ray diffraction, which indicated that the formation of AlPd alloy was believed to play a key role for the formation of low Ohmic contacts. The first-principle calculation indicated that the surface modification by oxygen plasma could increase the work function of AlN and therefore benefit the formation of Ohmic contacts. This result can promote the application prospects of AlN in deep ultraviolet optoelectronic devices and high frequency and high power RF devices.

Semipolar (11–22) AlN Films Grown by Hydride Vapor Phase Epitaxy for Schottky Barrier Diodes

“…Previous reports have confirmed that an AlN ohmic contact is established through the formation of Al–Au, Au–Ti, and Al–Ni alloys . Moreover, the performance of AlN ohmic contacts is assessed by the circular transmission line (CTLM) model . In one of the CTLM contacts shown in Figure b, r and R denote the radius of the inner circular contacts (ranging from 80 to 98 μm) and the radius of the outer circle (100 μm), respectively.…”

“…26 Moreover, the performance of AlN ohmic contacts is assessed by the circular transmission line (CTLM) model. 27 In one of the CTLM contacts shown in Figure 3b, r and R denote the radius of the inner circular contacts (ranging from 80 to 98 μm) and the radius of the outer circle (100 μm), respectively. The current versus voltage (I−V) curves of the CTLM contacts annealed at 950 °C for 30 s are shown in Figure 3c, enabling the calculation of specific contact resistivity.…”

Resonant electron confinement and sheath expansion heating in magnetized capacitive oxygen discharges

“…oxygen) discharges are of practical significance [28,[33][34][35][36][37][38][39][40][41][42], motivated by their important applications, e.g. in the fields of reactive-ion etching [43,44] and modifications of various surfaces [45][46][47]. Generally, capacitive oxygen discharges operate in the electronegative regime in the presence of only a few electrons.…”