Effects of Ga doping on optical and structural properties of ZnO epilayers

• Effects of Ga incorporation on electrical, structural and optical properties of ZnO epilayers are systematically studied by employing structural and optical characterization techniques combined with electrical and secondary ion mass spectrometry measurements. A non-monotonous dependence of free electron concentrations on Ga content is observed and is attributed to defect formation and phase separation. The former process is found to dominate for Ga concentrations of around 2-3x1020 cm-3. corresponding defects are suggested to be responsible for a broad red emission, which peaks at around 1.8 eV at K. Characteristic properties of this emission are well accounted for by assuming intracenter transitions at a deep center, of which the associated Huang-Rhys factor and mean phonon energy are determined. For higher Ga doping levels, the phase separation is found to be significant. It is that under these conditions only a minor fraction of incorporated Ga atoms form shallow donors, which leads to the observed dramatic decrease of carrier concentration.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

ZnO

Doping

Defect

NATURAL SCIENCES

NATURVETENSKAP

Semiconductor physics

Halvledarfysik

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