A new experimental setup for temperature difference method (TDM) was designed and their growth parameters were optimized for GaAs growth on (0 0 1) GaAs substrates. In the setup, the substrate is directly cooled by flowing H-2 to the backside. This is very useful to locally cool the substrate with an extreme high efficiency, which helps to prevent the mixture of growth modes between TDM and other growth modes like step cooling. The cross-sectional observations of scanning electron microscope show that the growth rate was roughly proportional to the H-2 flow, and the thickness of the growth was also proportional to the growth time. This indicates that the growth was chiefly driven by the temperature difference in the melt. Although the grown layers were not extremely uniform, the growth rate of more than 3 mu m/h was achieved. A very thick layer as thick as 360 mu m was obtained by increasing the growth time up to 100h. TDM was also applied to microchannel epitaxy of GaAs. A microchannel epitaxial layer whose width is as large as 84 mu m was laterally grown with a fine ratio of the width to the thickness of 13. (C) 2007 Elsevier B.V. All rights reserved.