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Influence of RIE- induced damage on luminescence and electron transport properties of AlGaAs-GaAs heterostructures.
Einfluss von RIE-induzierten Strahlenschäden auf Lumineszenz- und Elektronentransporteigenschaften von AlGaAs-GaAs Heterostrukturen
Reactive ion etching induced damage was systematically studied by photoluminescence (PL), cathodoluminescence (CL) and electronic microwave absorption in GaAs/AlGaAs multiple quantum well (MQW) and two-dimensional electron gas (2DEG) heterostructures. Using QW's of differing widths at various depths, PL and CL characterization of the individual quantum wells allowed a depth sensitive detection of RIE induced damage. Etching was done with CCl sub 2 F sub 2 at constant pressure and exposure time, while the bias voltage was successively increased from 55 to 320 V. A remarkable degradation in PL-intensity was observed for the topmost 1 nm QW located 30 nm beneath the surface, even at the lowest etch bias voltage. In 2 DEG heterostructure samples investigated electrically, both mobility and carrier concentration of the 2 DEG were seen to be strongly reduced. After illumination however, the initial values were almost completely restored, indicating that RIE damage predominantlyreduces the e lectron supply efficiency of the AlGaAs barrier, whereas the 2 DEG channel itself is not severely degraded even at the highest etch bias voltage.