Properties of Amorphous Calcium-Doped Copper–Aluminum Oxide Thin Films
Date Issued
2010
Date
2010
Author(s)
Chang, Hung
Abstract
Copper aluminum oxide is one interesting p-type transparent conducting oxide, which can be obtained by room-temperature sputtering. However, the as-deposited copper alumina oxide thin films are amorphous and have poor electrical propertied. Here, we try to doped the thin films with calcium to improve their electrical conductivity. We further made the bipolar junction transistors (BJT) by integrating copper aluminum oxide thin film with zinc oxide thin films, and the optical and electrical characteristics of the device were evaluated.
Thin films were sputtered from calcium doped copper aluminum oxide target at conditions of RF power = 100W, argon flow rate = 15sccm, and working pressure = 2mtorr. The oxygen flow rate and the target composition were varied. We used XRD to confirm that the thin films were amorphous. Their resistivity was obtained by four-point measurement. We found that thin film sputtered from Ca0.2CuAl0.8O2 target at oxygen flow rate of 10sccm had the lowest resistivity of 120Ω.cm.SIMS and EDS showed that the ratio of copper and aluminum was about 2:1. Low-temperature conductivity measurement indicated that there thin films were thermal-activation type semiconductor and variable-range hopping will occur under 190K.
The copper aluminum oxide thin films were futher integrated with zinc oxide thin films to form AZO/ Ca0.2CuAl1.8O2/ ZnO npn BJT, and find the β value of 1.1 and optical transmittance of 64% were obtained.
Subjects
CuAlO2
Copper–Aluminum Oxide
Amorphous
sputter
Type
thesis
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