We present measurements of the electron Hall mobility in n-type GaAs1−xBix epilayers. We observed no significant degradation in the electron mobility with Bi incorporation in GaAs, up to a concentration of 1.2%. At higher Bi concentration (≥1.6%) some degradation of the electron mobility was observed, although there is no apparent trend. Temperature dependent Hall measurements of the electron mobility suggest neutral impurity scattering to be the dominant scattering mechanism.

[1] A balloon campaign was conducted in summer, 1999, to measure the stratospheric electromagnetic fields associated with sprites. Ground observations for detection of sprites included low light level TV (LLTV) observations from three sites. Flight 1 flew from Palestine, Texas at 01:14:31 UTC to 09:45:00 UTC on 07/06/1999. Flight 3 of the campaign flew from Ottumwa, Iowa at 00:39:32 UTC to 11:12:00 UTC on 08/21/99. During flight 3, 26 sprite halos associated with positive cloud-to-ground (+CG) strokes and 17 ÀCG sprite halos were observed. Of these, 22 +CG and 12 ÀCG sprite halos were observed by the ground observatories. Seven of the +CG and all 17 ÀCG halos were not followed by sprites. Next the balloon data were examined during and after the times of the recorded NLDN strokes during 4.1 hours of data. An additional 88 ÀCG TLEs were found in the flight 3 data and 56 TLEs (7 +CG, 49 ÀCG) were found in the flight 1 data. It appears that ÀCG TLEs, mostly spriteless halos, occurred 5 -7 times more often than the +CG TLEs. The halo appears to be a fundamental mesospheric response to lightning.

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An eight-band Kane Hamiltonian modified for the strain has been used to describe the electronic states of the highly strained zincblende GaAs1−xNx. Conduction and valence band offsets of GaAs1−xNx with respect to InAs on InP(111) have also been investigated for different nitrogen (N) concentrations. A critical concentration of N is found, which marks the onset of type-I to type-II band alignment for GaAs1−xNx/InAs on InP(111). The effect of nitrogen on the conduction band of GaAs1−xNx has been described by the band anticrossing model. The strain balanced InAs /GaAs1−xNx short period superlattice on InP is predicted to reach operating wavelengths beyond .