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Crystallographic Orientation Control

IP.com Disclosure Number: IPCOM000091195D
Original Publication Date: 1969-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Kay, E: AUTHOR [+2]

Abstract

The technique is for the preparation of ZnO thin films at low temperatures. The structural orientation of the film can be varied in a controlled manner on polycrystalline substrates. A standard DC glow discharge sputtering method is employed for the production of ZnO films. Zinc metal is sputtered in an argon-oxygen mixture. Zinc atoms are ejected from the target cathode and are subsequently deposited onto a clean temperature controlled substrate where they react with molecular oxygen or oxygen atoms which are formed in the discharge. The temperature controlled substrate allows an ion current to be extracted from the plasma.

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Crystallographic Orientation Control

The technique is for the preparation of ZnO thin films at low temperatures. The structural orientation of the film can be varied in a controlled manner on polycrystalline substrates. A standard DC glow discharge sputtering method is employed for the production of ZnO films. Zinc metal is sputtered in an argon- oxygen mixture. Zinc atoms are ejected from the target cathode and are subsequently deposited onto a clean temperature controlled substrate where they react with molecular oxygen or oxygen atoms which are formed in the discharge. The temperature controlled substrate allows an ion current to be extracted from the plasma. Thus in addition to the condensible sputtered particles and molecular or atomic gas species arriving at the substrate, there is a continuous bombardment of the film surface by sputtering gas ions of controlled energy.

A 4-1/2 inch diameter by 1/2-inch thick zinc disk with a purity of 99.999% is used for the target cathode. The cathode-anode spacing is 4.5 cm. The sputtering occurs at an applied cathode potential of 3000 volts in a 10% oxygen- 90% argon mixture at a pressure of 30 x 10/-3/ torr. ZnO films are deposited at a rate of 3.7 angstroms/sec on gold substrates held at -100 degrees C and zero bias voltage. The gold can be in the form of a foil or an evaporated layer. The films as deposited have a resistivity of approx. 10/11/ omega-cm. X-ray diffraction show the films to be highly oriented such that the c-axis of the hexagonal ZnO crystal is oriented perpendicular to the plane of the substrate. The relative strength of the (0002) reflection of sputtered ZnO on gold indicates a high degree of c-axis orientation.

When polycrystalline zinc substrates are substituted for gold under the same low-temperature conditions, the deposition rate increases to 4.6 angstroms/s...