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CHARACTERIZATION OF ELECTRON CYCLOTRON RESONANCE PLASMA-DEPOSITED HYDROGENATED AMORPHOUS SILICON AND RELATED ALLOY FILMS J.M. ESSICK*, F.S. POOL**, Y.H. SHING** AND M.J. HOLBOKE* * Department of Physics, Occidental College, Los Angeles, CA 90041 **Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109

ABSTRACT We characterized a-Si:H films deposited by the electron cyclotron resonance (ECR) microwave plasma-enhanced CVD technique with the purpose of comparing ECR film quality with that of films deposited by the if plasma-enhanced CVD method. These ECR films were deposited in the 1-10 mT pressure region under a variety of growth conditions. Our investigations reveal the following typical properties for intrinsic ECR-deposited a-Si:H: (1) high photosensitivity as indicated by a light-to-dark DC conductivity ratio of up to 2x106 , (2) a Tauc gap in the range of 1.75-1.85 eV, (3) an Urbach slope of 45-60 meV as determined by CPM and (4) an integrated deep defect density of 0.5-2x10`1 cm- 3 with Ec - E, = 0.74-0.87 eV as determined by drive level profiling and junction capacitance vs. temperature scans. Variations of these quantities with deposition temperature, hydrogen dilution and magnetic field profile are discussed. Our results indicate that ECR-deposited a-Si:H is of comparable quality to a-Si:H deposited by the rf plasma glow discharge technique. ECR deposition conditions for a highly conductive type of a-Si:H film also are discussed. This material, while only slightly photosensitive and possessing an Urbach slope of over 100 meV, has a light DC conductivity of 3x10 4 (Qcm)- 1 . Boron doping of this material produces a conductivity of 5x10 2 (0cm)- 1 . INTRODUCTION Hydrogenated amorphous silicon (a-Si:H) and related alloy thin films are typically deposited by the conventional radio frequency plasma-enhanced chemical vapor deposition (if PECVD) method. The rf PECVD ("glow discharge") process has been extensively investigated and produces top-quality materials for photovoltaic and other device applications. However, the susceptibility of these films to degrading metastable effects has inhibited the full realization of amorphous silicon's potential in device applications. Investigation of alternative deposition methods provides one fruitful path to follow in the search for a solution to a-Si:H's stability problems. Electron cyclotron resonance (ECR) microwave PECVD is one such newly emerging thin film deposition technology. The ECR PECVD method is a remote plasma deposition technique which offers the potential for great control over the deposition process. In this paper, as a first step towards a deeper understanding of ECR deposition, we employ a battery of material characterization techniques to show that the ECR PECVD method produces a-Si:H thin film samples of comparable quality to films produced by the glow discharge method. ECR SAMPLE GROWTH Our ECR microwave PECVD system consists of the stacked arrangement of an ECR ion source and a deposition chamber equipped with a heated sample