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Determination of axial and lateral exciton diffusion length in GaN by electron energy dependent cathodoluminescence
Ist Teil von
Journal of applied physics, 2016-08, Vol.120 (8)
Ort / Verlag
Melville: American Institute of Physics
Erscheinungsjahr
2016
Quelle
AIP Journals (American Institute of Physics)
Beschreibungen/Notizen
We demonstrate the application of low-temperature cathodoluminescence (CL) with high lateral, depth, and spectral resolution to determine both the lateral (i.e., perpendicular to the incident primary electron beam) and axial (i.e., parallel to the electron beam) diffusion length of excitons in semiconductor materials. The lateral diffusion length in GaN is investigated by the decrease of the GaN-related luminescence signal when approaching an interface to Ga(In)N based quantum well stripes. The axial diffusion length in GaN is evaluated from a comparison of the results of depth-resolved CL spectroscopy (DRCLS) measurements with predictions from Monte Carlo simulations on the size and shape of the excitation volume. The lateral diffusion length was found to be (95 ± 40) nm for nominally undoped GaN, and the axial exciton diffusion length was determined to be (150 ± 25) nm. The application of the DRCLS method is also presented on a semipolar
(
11
2
¯
2
)
sample, resulting in a value of (70 ± 10) nm in p-type GaN.