Liquid phase epitaxy of AlxGa1?xP on GaP and its application to double heterostructure light modulators

Single- and double-heterojunction structures of Al_xGa_1?xP/GaP were grown by liquid phase epitaxy and their opto-electronic properties were characterized. Using a starting growth temperature of 900°C, a background impurity level in undoped Al_0.5Ga_0.5P of 1 × 10¹⁶ cm^-3 (p-type) is obtained. The growth rate of Al_xGa_1?xP was very low. An almost intrinsic layer exists at the p-n Al_xGa_1?xP/GaP heterojunction interface due to the interdiffusion of the dopants. By using a rotating slide liquid phase epitaxial growth technique, we have made a high efficiency light modulator from a Al_xGa_1?xP/GaP double heterostructure. The employment of a dummy crystal resulted in very good reproducibility of the GaP waveguide layer thickness. Light is well confined in the GaP layer and a voltage difference, V_π, of 6 V is enough to obtain the phase difference, π, between TE and TM modes.