Splitting of Photoluminescence Spectra and Negative Differential Resistance Caused by the Electric Field Induced Resonant Coupling of Quantized Levels in GaAs–AlGaAs Multi-Quantum Well Structures

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Abstract
Effects of the perpendicular electric field F z on the photoluminescence (PL) and photocurrent were studied at 77 K in a 150 A-GaAs/150 Al0.3Ga0.7As multi-quantum well structure having 15 periods. When F z was increased, the main PL peak was found to shift toward the longer wavelength and its intensity diminished due to the carrier leakage from the quantum well, in accordance with prediction. When the field exceeded a critical value, however, a new PL peak emerged unexpectedly, giving rise initially to a double peaked spectrum and subsequently dominating the initial peak. The appearance of the double peaked structure was found to be accompanied by a negative differential resistance in photocurrent measurement. These unusual phenomena are ascribed to the electric field-induced resonant coupling of the two lowest quantum levels in the adjacent quantum wells.