Hafnium oxide (HfO 2 ) thin films were deposited from tetrakis͑ethylmethylamino͒hafnium ͑TEMAH͒ and ozone (O 3 ) by atomic layer deposition ͑ALD͒ on 200 mm silicon wafers. The O 3 half-reaction shows good saturation behavior. However, gradual surface saturation is observed for the TEMAH half-reaction. Within wafer non-uniformity of less than 1% and step coverage of about 100% were achieved for trenches with aspect ratio of around 40:1. The film thickness increased linearly as the number of cycles increased. From susceptor temperatures of 160-420°C, the lowest deposition rate ͑Å/cycle͒ and the highest refractive index is observed at 320°C. The atomic ratio of hafnium to oxygen determined by Rutherford backscattering is 1:2.04 for the films deposited at 320°C. The carbon and hydrogen content determined by secondary ion mass spectroscopy ͑SIMS͒ decreased as the susceptor temperature increased from 200 to 320°C. Lower carbon and hydrogen levels were obtained in the control films made with H 2 O than the films made with O 3 . A reaction mechanism of the TEMAH ϩ O 3 ALD process is discussed. The results show that an O 3 -based ALD HfO 2 deposition is promising for microelectronic applications.

High-quality amorphous hydrogenated germanium has been deposited using the diode rf glow discharge method out of a gas plasma of GeH4 and H2. The optical, electrical, and structural properties of this material have been extensively characterized. The optical and electrical properties are all consistent with material containing a low density of defect related states in the energy gap. In particular, this material has an ημτ=3.2×10−7 cm2/V, ratio of photocurrent to dark current of 1.3×10−1, and flux dependence of the photocurrent with γ=0.79 at 1.25 eV measured using photoconductivity, a μτ=4×10−8 cm2/V measured using time of flight, an Urbach energy of 51 meV and α at 0.7 eV of 8.3 cm−1 measured using photothermal deflection spectroscopy, a dangling bond spin density of 5×1016 cm−3 measured using electron spin resonance, photoluminescence with a peak energy position of 0.81 eV and full width at half maximum of 0.19 eV, an activation energy of 0.52 eV and σ0 of 6.1×103 (Ω cm)−1 measured using dark conductivity, and an E04 band gap of 1.24 eV measured by optical absorption. The structural measurements indicate a homogeneous material lacking any island/tissue and columnar structure when investigated using transmission and scanning electron microscopy, respectively. Hydrogen concentrations calculated from infrared and gas evolution measurements can only by reconciled by postulating a large quantity of unbonded hydrogen whose presence is confirmed using deuteron magnetic resonance. The bonded deuterium component, as seen in this film using DMR, has a spin-lattice relaxation time of the order of 4000 s. The differential scanning calorimetry measurement shows crystallization occurring at 421 °C and the presence of large compressive stresses has been confirmed using a bending-beam method. The experimental details necessary to interpret the quantities quoted here are set out in the text which follows. It is considered that the very good optical and electrical properties of this as yet unoptimized material are directly related to the structural properties detailed above.

Radio frequency glow discharge chemical vapor deposition has been used to deposit thin films of a-Si1−xGex:H which possess optoelectronic properties that are greatly improved over any yet reported in the range of x⩾0.6. These films were deposited on the cathode (cathodic deposition) of an rf discharge. Their properties are assessed using a large variety of measurements and by comparison to the properties of alloys conventionally prepared on the anode (anodic deposition). Steady state photoconductivity measurements yield a quantum-efficiency-mobility-lifetime product, ημτ, of (1–3)×10−7 cm2 V−1 for 1.00⩾x⩾0.75 and (6–10)×10−8 cm2 V−1 for 0.75⩾x⩾0.50, and photocarrier grating measurements yield ambipolar diffusion lengths several times greater than previously obtained for alloys of large x. It is confirmed that the improvements in phototransport are not due to a shift in the Fermi level. In fact, results of recent measurements on lightly doped samples strongly suggest that for these cathodic alloys neither photocarrier is dominant [(μτ)e≈(μτ)h]. The improvements are attributed in large part to the reduction of long range structural heterogeneity observed in x-ray scattering and electron microscopy, and partly to the reduction in midgap state density. In spite of the superior properties, an assessment of the data of the cathodic alloys suggests that alloying introduces mechanisms detrimental to transport which are not present in a-Si:H or a-Ge:H. The Urbach tail width is 42±2 meV for cathodic a-Ge:H and 45±2 meV for cathodic a-Si1−xGex:H and is constant with x. From differences in the band edges and tails we infer that the atomic bond ordering is different between the cathodic and anodic alloys. For a given composition the cathodic alloys have roughly an order of magnitude lower midgap state density than do the anodic alloys, and both midgap densities increase exponentially with x, consistent with defect creation models from which the lower midgap density can be attributed to a larger band gap and decreased valence band tail width. A photoluminescence peak is observed with an intensity roughly an order of magnitude greater than for the anodic alloys, and a significantly different peak energy. Section VII E provides an overview of the results and conclusions. The improved properties of these alloys have significant implications for current and future device applications.

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