Electro-optical device with inverted transparent substrate and method

Abstract

An electro-optical device with a transparent substrate is produced by epitaxially first growing the device layers, followed by that of the transparent substrate layer on an opaque wafer. The opaque wafer is subsequently removed. The device layers have dopants with sufficient low diffusivities that their electronic characteristics are not adversely affected by long exposure to elevated temperature during the growth of the transparent substrate layer. In a liquid phase epitaxy (LPE) method, a repeated temperature cycle technique is used where the temperature is repeatedly raised up each time after cooling to provide a large cooling range for growing a sufficiently thick substrate layer or a series of device layers. In between growths and during the temperature heat-up periods, the device is stored within the LPE reactor. In other embodimens, the device is either temporarily removed from the LPE reactor or is transferred to another reactor. When a epitaxial layer is oxidizable, a non-oxidizable cap is temporarily grown on it in between growths and during the temperature heat-up periods. The cap is subsequently removed by melting back at an elevated temperature just prior to the growth of a next layer.