Pt/Ti/SiO2/Si structures have been studied to investigate the structural, chemical, and microstructural changes that occur during annealing. Grain growth of the as-deposited Pt columns was observed after annealing at 650 °C, and extensive changes in the Pt microstructure were apparent following a 750 °C anneal for 20 min. In addition, two types of defects were identified on the surfaces of annealed substrates. Defect formation was retarded when the surface was covered with a ferroelectric film. Concurrent with the annealing-induced Pt microstructure changes, Ti from the adhesion layer between the Pt and the SiO2 migrated into the Pt layer and oxidized. It was shown with spectroscopic ellipsometry and Auger electron spectroscopy that for long annealing times, the titanium oxide layer can reach the Pt surface. Consequently, at the processing temperatures utilized in preparing many ferroelectric thin films, the substrate is not completely inert or immobile. The changes associated with Ti migration could be especially problematic in techniques that require the substrate to be heated prior to film deposition.

Magnetron reactive ion etching of GaN in BCl3 plasmas was investigated as a function of cathode power density, flow rate, and pressure. GaN etch rates were achieved (350 nm/min), which were twice the highest etch rate previously reported, and at low cathode bias voltages (<100 V). Auger electron spectroscopy measurements revealed the etched surfaces to be Ga deficient to a depth of 10 nm, with a surface chlorine residue of <1 at. %. Magnetron dry etching appears well suited to applications such as mesa definitions for photonic devices in the GaN materials system.

Dry etching-induced surface damage and contamination on SiC have been investigated for electron cyclotron resonance (ECR) plasma etching and conventional reactive ion etching (RIE) using a CF4/O2 gas mixture. Auger electron spectroscopy shows that there is no residue on the ECR etched surfaces and sidewalls of the etched structures. In contrast, the conventional RIE process leaves residues containing large amounts of Al, F, and O impurities on the surfaces and the etched sidewalls. Pd Schottky diodes on the ECR etched surface show a near-ideal diode characteristics with ideality factor of 1.06, indicating a good surface quality. Pd Schottky diodes on the conventional RIE etched surface, however, have a substantially reduced barrier height from 1.05 eV for the as-grown sample to 0.64 eV and a high ideality factor of 1.27, indicating a substantially damaged surface. Significant free-carrier reduction is observed in the RIE etched sample.

A shallow Pd/Ge/Ti/Pt/ohmic contact for both n- and p-GaAs has been investigated. The contacts were rapid thermally annealed in N2 for 15 s at temperatures from 350 to 550 °C. The lowest average specific contact resistances were 4.7×10−7 and 6.4×10−7 Ω cm2 for the n- and p-GaAs, respectively, when the n-GaAs was doped with Si to 2×1018 cm−3 and the p-GaAs was doped with carbon to 5×1019 cm−3. Electrical measurements and Auger depth profiles showed that the contacts were stable as they remained ohmic after an anneal at 300 °C for 20 h for both n- and p-GaAs. The p contact is more stable than the n contact at the higher temperatures where there is more As outdiffusion as determined by Auger depth profiles. Transmission electron microscopy showed that the interfaces between the p-GaAs and the contacts were smooth for both as-grown and annealed samples, and no oxides were detected.