AVS 53rd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP15
New Sublimation Reactor for Epitaxial Growth of II-VI Films

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Vacuum Technology Poster Session
Presenter: L.J. Rascon, University of Texas at El Paso
Authors: L.J. Rascon, University of Texas at El Paso
L.C. Romo, University of Texas at El Paso
S. Rogers, University of Texas at El Paso
S. Quinones, University of Texas at El Paso
J. McClure, University of Texas at El Paso
D. Zubia, University of Texas at El Paso
Correspondent: Click to Email
Close Spaced Sublimation (CSS) is a well established technique for deposition of polycrystalline CdTe thin films for solar cell applications. However, due to the very high growth rates at usual operating conditions, the technique has not been used for high quality films for advanced electronic applications. Our group has recently discovered operating conditions that yield smooth epitaxial CdTe thin films. This presentation will discuss a new CSS reactor designed at University of Texas El Paso which permits deposition of up to three different materials in layers as thin as a few tens of angstroms. Layers can be repeated as often as needed and with varying thicknesses if desired to build up a final device structure. The new reactor is able to deposit unary, binary and ternary semiconductor alloys and was conceived as a low cost alternative to high quality epitaxial crystal deposition techniques such as the costly molecular beam epitaxy (MBE). This poster presents the conceptual and physical design as well as the construction and operation of the new CSS reactor. The system performs depositions on a vertical arrangement in a vacuum of 5x10@sub -1@ Torr. Furthermore, it employs two servomotors. The first, to control the substrate to source distance, and the second, to position the substrate directly on top of one of the three sources. Hydrogen, helium and oxygen can flow during deposition to create different environments. A PID-loop controlled throttle valve manages the pressure to any set point regardless of the gas inflow. Moreover, the temperature of the three sources and the substrate are independently administered by three button heaters and a flat plate heater, respectively. Finally the complete deposition process is controlled by a computer program made in LabVIEW. Preliminary results of epitaxial CdTe films grown in the CSS reactor using very small temperature gradients will be presented.