Electron-cyclotron-resonance plasma etching of the ZnO layers grown by molecular-beam epitaxy

Abstract

Etching of high-quality ZnO layers grown by molecular-beam epitaxy was examined by using electron-cyclotron-resonance plasma etching. Etching rates of ZnO layers were larger using CH4 than CF4, and four times more enhanced by using a mixture of the two gases. For a ZnO surface covered with photoresist layers by the plasma-etching procedure, degradation was mostly recovered by thermal annealing in an O2 atmosphere at the proper temperatures. This was found to be effective for the recovery of the layers.

Characteristics of a Zn0.7Mg0.3O∕ZnO heterostructure field-effect transistor grown on sapphire substrate by molecular-beam epitaxy

“…The FE elucidated is well accorded with the Hall in the previous section, suggesting a sharp interface at the ZnO well/bottom Zn 0.7 Mg 0.3 O barrier with no degradation of crystalline quality despite the ion bombardment during ECR etching. As has been reported elsewhere, 9 we believe that the annealing process at 400°C to obtain ohmic contact was also effective in recovering the damage of ion bombardment. This large FE as high as 140 cm 2 / V s is nearly 100 times larger than those reported for conventional TFTs with polycrystalline ZnO channels grown on glass substrates.…”

“…We employed for the etching an Elionix-made EIS-200ER system operated at 2.45 GHz with a microwave power of 80 W and a dc biasing of 850 V in a 0.01 Pa mixture gas of CF 4 and CH 4 ͑2:3͒. 9 Schematic of the HFET is shown by Fig. 1͑a͒ with a top view photograph of Fig.…”

High‐field characteristics of ZnO and ZnO/ZnMgO heterostructures

“…The device fabrication was carried out using conventional photolithography. First, the device periphery was defined by electron-cyclotron resonance plasma etching using a mixture of CH 4 and CF 4 [14]. The source and drain ohmic contacts were formed by evaporating Ti (20 nm)/Au (200 nm) for devices fabricated using the thick ZnO and the SH structures since nonalloyed ohmic contacts can be formed on the structures which have no ZnMgO cap layer.…”

Polarization-induced two-dimensional electron gas at Zn1−xMgxO/ZnO heterointerface

“…Although some of these strong points overlap with another wide bandgap semiconductor GaN, particular advantages of ZnO include bulk growth capability, amenability to conventional chemical and plasma-etching techniques [2], low growth temperature, high radiation hardness [3], and nearly double exciton binding energy.…”