GROWTH OF PSEUDOMORPHIC HIGH ELECTRON-MOBILITY HETEROSTRUCTURES BY ATMOSPHERIC-PRESSURE METALORGANIC CHEMICAL VAPOR-DEPOSITION

Pseudomorphic high electron mobility heterostructures are demonstrated by atmospheric pressure metalorganic chemical vapor deposition for the first time. Transmission electron microscopy (TEM), variable temperature Hall effect measurements, Shubnikov-de Haas measurements, and photoreflectance were applied to characterize the heterostructures. TEM micrographs of the cross section reveal sharp heterojunction interfaces. Variable temperature Hall effect measurements show a monotonic increase in mobility as the temperature is lowered. With a spacer thickness of 120 Å, a peak mobility of 80 000 cm2/V s at 20 K and a sheet carrier concentration of 1.05×1012 cm-2 are obtained. Similarly, a thinner spacer (60 Å) shows a peak mobility of 57 000 cm2/V s at 25 K with a sheet carrier concentration of 1.40×1012 cm -2. Shubnikov-de Haas measurements in magnetic fields up to 18.5 T show clear oscillations and the quantum Hall effect confirming the existence of a two-dimensional electron gas.