AVS 53rd International Symposium
    Electronic Materials and Processing Wednesday Sessions
       Session EM-WeM

Paper EM-WeM9
Influence of Nitrogen Incorporation on Electron Transport in Selectively Doped GaAsN/AlGaAs Heterostructures

Wednesday, November 15, 2006, 10:40 am, Room 2003

Session: New Directions in Compound Semiconductors
Presenter: Y. Jin, University of Michigan
Authors: Y. Jin, University of Michigan
M. Reason, University of Michigan
X. Bai, University of Michigan
H.A. McKay, University of Michigan
C. Kurdak, University of Michigan
R.S. Goldman, University of Michigan
Correspondent: Click to Email
Dilute nitride (In)GaAs(N) alloys are useful for infrared laser diodes, high efficiency solar cells, and high performance heterojunction bipolar transistors. Typically, increasing N incorporation results in substantially lower electron mobilities than (In)GaAs. The precise role of N in lowering the electron mobility is not well understood. To determine the N-related electron scattering effects in GaAsN, with minimal contributions from ionized impurity scattering, we have studied modulation-doped AlGaAs/GaAs(N) heterostructures, with Si dopants in the AlGaAs barrier layer spatially separated from the undoped GaAs(N) channel layer. AlGaAs/GaAs(N) heterostructures and corresponding GaAs(N) bulk-like films with a variety of N concentrations were grown via molecular-beam epitaxy. Samples containing GaAs or GaAsN as the channel layer are referred to as "control" or "nitride" samples, respectively. The substitutional and interstitial N concentrations were determined using nuclear reaction analysis and Rutherford backscattering spectrometry studies of the bulk-like GaAsN films. Low T magnetoresistance and Hall measurements of the heterostructures reveal similar free carrier concentrations(in the dark) for the nitride and control samples, suggesting that N is not acting as a trapping center. Manipulation of the channel carrier density via front-gating and illumination with a light emitting diode reveals electron mobilities which increase with carrier density for all samples. For the control samples, µ~n^@gamma@, where @gamma@ is typically 1~1.5, suggesting the dominant scattering mechanism is long-range ionized impurity scattering. For the nitride samples, the mobility saturates for n > 1.5x10@super 11@cm@super -2@, suggesting that short-range N-induced neutral scattering is the dominant scattering source in GaAsN. The effects of varying substitutional and interstitial N concentrations on the transport properties of (In)GaAsN will also be discussed.