High-throughput high-yield fabrication of selectively doped AlxGa1−xAs/GaAs heterostructures by molecular beam epitaxy

A new etching procedure for GaAs substrates and a modified configuration of selectively doped n-AlxGa1−xAs/GaAs heterostructures have been developed for molecular beam epitaxy to reduce the density of oval defects and the epitaxial growth time. The new simplified substrate preparation method reduces the oval defect density to less than 100 cm−2 and allows storage of prepared substrates in air under dust-free conditions for several weeks without any degradation. Modification of the layer structure reduces the throughput time to less than 30 min per wafer including epitaxial growth, wafer exchange, heat and cool times. High mobilities of the two-dimensional electron gas and excellent reproducibility are achieved. The new process uses the favorable growth rate of <1 μm/h for GaAs and thus allows growth of nearly 500 high-quality heterostructure wafers for device fabrication without exposure of the growth chamber to atmosphere for effusion cell recharging.