No abstract

No abstract

InAs layers were deposited on glass substrates by molecular-beam deposition at substrate temperatures of 180 -240 C at As/ In beam equivalent pressure (BEP) ratios of 3 -30. X-ray diffraction (XRD) patterns indicated that the InAs layers are polycrystalline and are more preferentially textured in the (111) plane when deposited at higher temperatures and lower As/In BEP ratios. Room-temperature Hall effect measurement showed that the films deposited at an As/In BEP ratio of 30 exhibit n-type conduction with electron concentrations of approximately 3 Â 10 18 cm À3 , being almost independent of substrate temperature. With decreasing As/In BEP ratio from 30 to 3 at a fixed substrate temperature of 240 C, the electron concentration decreased to 1:5 Â 10 18 cm À3 and the electron mobility increased to 610 cm 2 /(VÁs). Preliminary results of the deposition on plastic substrates showed an electron mobility of 460 cm 2 /(VÁs) when the layer was deposited at 280 C at an As/In BEP ratio of 30.

No abstract

Using secondary ion mass spectrometry, we have investigated the excess As concentration in InAs layers grown by molecular beam epitaxy at 150‐300 °C. A step‐like increase of the As/In ratio from the substrate to the epi layer was observed for the samples grown at lower temperatures than 250 °C. The excess As concentration averaged over the grown layer thickness reached 1.2×1020 cm–3 for the layer grown at 200 °C. Through the combination with the results of X‐ray diffraction, a proportional relation of Δa⊥/a = 2×10–24 δ [As] is deduced between the perpendicular lattice mismatch Δa⊥/a and the atomic density δ [As] of excess As in the unit of cm–3. Hall effect measurements at 77 K revealed that the electron concentration is much lower than the excess As concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)