Atomic layer epitaxy of group iv materials: Surface processes, thin films, devices and their characterization. Semiannual technical report, 1 July-31 December 1995
A seeding multi-step deposition process has been developed to nucleate and grow oriented diamond films on both (100) and (111) Ni substrates without graphite codeposition, as shown by SEM and micro Raman spectroscopy. Cross-sectional TEM and XRD confirmed the presence of a polycrystalline Ni4C interlayer between single crystal Ni and the oriented diamond crystals. The key to the process is a molten Ni-C-H surface layer that promotes the nucleation of oriented particles and suppresses graphitic deposition. The presence of atomic hydrogen is critical to lowering the melting temperature of this surface layer. Based on the results of this work, a model is proposed to explain the mechanism of oriented diamond nucleation. In related work, diamond has been grown from a Ni-C solution in the presence of atomic hydrogen. Current work is focused on determining the nature of the surface molten phase, and attempts to grow heteroepitaxial diamond from the liquid phase. Atomic layer epitaxy of CeO2 films on slightly off-oriented Si(100) substrates by pulsed laser ablation of a CeO2 target was achieved under ultra high vacuum conditions and at low temperatures. RHEED patterns observed after RTA at 1000 C in Ar for 5 and 10 min indicated that crystallization was partially obtained. The effects of annealing in forming gas at 500 C for 30 min and subsequent RTA in Ar at 100 C for 5 min on the stmcture were investigated. The C-V and I-V properties of the films were investigated. The films have large MOS capacitance but also have larger leakage currents compared to those of epitaxial CeO2 films on Si(111) substrates. However, improved leakage and breakdown characteristics were obtained with annealing in forming gas.
- Research Organization:
- North Carolina State Univ., Raleigh, NC (United States)
- OSTI ID:
- 250588
- Report Number(s):
- AD-A-303296/8/XAB; CNN: Contract N00014-91-J-1416; TRN: 61490446
- Resource Relation:
- Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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