Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 33: II-VI Halbleiter I

HL 33.7: Talk

Wednesday, March 26, 2003, 17:45–18:00, BEY/118

New approach toward green-yellow light emitters using ZnTe-based homoepitaxial structures — •Akio Ueta und Detlef Hommel — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee, 28334 Bremen

Fabrication of light emitting devices in the green-yellow wavelength regions is an important issue concerning semiconductor lasers. Up to now, ZnSe-based laser diodes in the wavelength region from 505 nm to 560 nm were achieved by our group. However, device lifetime is still a problem. One reason might be the compressive strain resulting from the lattice mismatch between the ZnCdSSe active layer and the GaAs substrate. Device fabrication under lattice matched conditions will therefore be a key issue. ZnTe has a bandgap energy in the pure-green wavelength region and the introduction of ZnTe-based alloys lattice matched to ZnTe substrates such as ZnMgSeTe and ZnCdSeTe is a promising option. In this work, ZnCdSeTe/ZnMgSeTe quasi-quaternary pn-junction light emitting diodes grown by molecular beam epitaxy emitting around 2.25 eV at room temperature are demonstrated. A ZnMgSeTe quasi-quaternary layer consists of ZnSe/ZnMgTe stacked layers lattice matched to ZnTe substrates. P-type and n-type ZnMgSeTe quasi-quaternary layers were realized by doping with N and Cl, respectively. Generally, an n-type ZnMgSeTe layer is very hard to obtain. However, a Cl doped ZnMgSeTe quasi-quaternary layer showed net carrier concentration nearly 1× 10¹⁸ cm⁻³. This might be caused by insertions of nano-cluster ZnSe:Cl into ZnMgTe contributing as effective donor centers.