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HL: Halbleiterphysik
HL 24: Bauelemente
HL 24.7: Vortrag
Samstag, 5. März 2005, 12:15–12:30, TU P-N229
A new opto-electronic device: A polarisation-sensitive, intensity-independent switch for 1.3 µ m — •Stefan Krämer1, J. Spieler1, S. Malzer1, S. Neumann2, W. Prost2, F.J. Tegude2, and G.H. Döhler1 — 1Technische Physik I, Universität Erlangen-Nürnberg — 2Halbleitertechnik, Universität Duisburg
Under specific growth conditions the quaternary semi-conductor InGaAsP forms a monoatomic superlattice in [111]B-direction, similar to some ternary materials. These ordered materials exhibit a strong absorption anisotropy for light polarised in [110] or [1-10] direction at near-bandgap photon energies. The quaternary InGaAsP, lattice-matched to InP, is particularly appealing for photonic device applications, as its bandgap can be adjusted to the standard wavelengths for optical communication (1.3 µ m and 1.55 µ m). We use the optical anisotropy for a polarisation-dependent opto-electrical switch. It consists of a strongly polarization dependent photo-FET-diode with ordered 1.3 µ m InGaAsP in the active region, which is grown on top of a polarization-independent reference-diode with disordered 1.5 µ m InGaAsP in the absorbing layer. The absorption layer thicknesses are designed such, that depending on polarisation the photocurrent in the reference diode is larger or smaller than in the photo-FET-diode. Accordingly, almost the whole voltage drops either on the photo-FET- or on the reference-diode, whence the n-channel conductance is either "off" or "on" depending on the polarisation. Switchting is observed for 100nW < PLaser < 1.5mW with Ion = 10mA, practically independent on the laser power. The switching contrast ranges between 3 and 7 orders of magnidude, depending on PLaser.