Thin-layer liquid phase epitaxy of InGaPAs heterostructures in short intervals (< 100 ms): Non-diffusion-limited crystal growth

Abstract

Data are presented showing that two different mechanisms control the LPE growth of InGaPAs in the step-cooled technique. An automated growth apparatus, which allows an accurate and reproducible selection of growth times as short as ~9ms, is used to study the thickness and the growth rate of InGaPAs layers as a function of growth time for times ranging from ~9ms to ~20s. For long intervals the measured InGaPAs epilayer thickness is shown to vary as the square root of the growth time, as expected for the case of diffusion-limited growth. When the growth period is reduced to < 200ms , the quaternary layer thickness is greater than the diffusion-controlled value and, in addition, is practically independent of the growth time. Auger depth profile data on InGaPAs layers grown from ~ 9ms to ~ 120ms are presented showing that layers are uniform in composition. Photoluminescence data on InGaPAs layers grown under non-diffusion limited conditions are shown to be different in composition than the relatively thick layers grown under diffusion-limited conditions, at longer times, from melts with the same liquidus compositions. Data are presented indicating the existence of both of these distinct compositions in a single ~ 800 Å InGaPAs layer grown in ~ls. It is shown that thick InGaPAs layers of uniform composition can be grown, by the step-cooled LPE process, by stacking a number of thin layers grown in short intervals. Data are presented indicating that thin-layer stacks can be used to improve the performance characteristics of heterostructure lasers.