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We report experimental evidence of excitonic spin-splitting, in addition to the conventional Zeeman effect, produced by a combination of the Rashba spin-orbit interaction, Stark shift and charge screening. The electric-field-induced modulation of the spin-splitting are studied during the charging and discharging processes of p-type GaAs/AlAs double barrier resonant tunneling diodes (RTD) under applied bias and magnetic field. The abrupt changes in the photoluminescence, with the applied bias, provide information of the charge accumulation effects on the device.The effect of the spin-orbit (SO) interaction in quasitwo-dimensional (Q2D) systems has attracted renewed attention in recent years. The topic has been on the focus of many optical and transport investigations of spin-related phenomena in nanoscopic systems [1,2,3], a subject of great fundamental and technological interest [4,5,6,7]. In this letter, we address experimental evidence of electric field coupling to the spin degree of freedom of carriers in RTD; here in particular, the prevailing influence can be attributed to the SO and Stark effects on the hole electronic structure. These interactions are relevant to the study of the internal electric fields and the charge accumulation in the structure. The simultaneous investigation of optical and transport properties at high magnetic and electric parallel fields, has permitted a thorough characterization of the main processes involved in the system response. The novelty of this result consists of the optical detection of electric field modulation of the effective spin-splitting beyond the Zeeman effect and its unambiguous correlation to the transport mechanisms which is responsible for the charge buildup in the states of the RTD.This study is carried out on a symmetric p − i − p GaAs/AlAs RTD, that has been previously used to characterize hole space charge buildup and resonant effects in a magnetic field [8]. The structure is in the form of a 400µm diameter mesa with a metallic AuGe annular top contact to allow optical access. The diode was mounted in a superconducting magnet and the emission spectra were recorded using a double spectrometer coupled to a CCD system with polarizer facilities to select left (right) σ +(−) configurations. When light from an Ar + laser is focused close to the surface, minority electrons are created [8]. As the bias approaches a resonant condition, the carrier density inside the QW increases and then decreases, resulting in the negative differential resistance (NDR) region when the resonance is traversed. The photo-generated electrons tunneling into the QW layer can recombine with the injected holes or tunnel out of the well layer. These processes are represented schematically in the Fig. 1 (a).The I − V characteristics, shown in Fig. 1 (b), displays a series of peaks associated with the injected holes (I dark ) from the hole accumulation layer formed in the outside interface of the diode (see Fig. 1 (a)). Under illumination, an increase of current is observed (I light ) due to ...

We have investigated polarization-resolved photoluminescence under applied voltage in p-i-p GaAs/ AlAs double-barrier diodes. We have observed oscillations in the degree of polarization up to 36% at B = 15 T with sign reversals occurring near to the hole subband resonances. At high voltages a polarization saturation up to 25% at B = 15 T is observed. The data are interpreted by using simulations based on a simple theoretical model that considers spin conservation for tunneling and the relaxation processes for carriers at Zeeman states in the quantum well. Our work offers the prospect for the development of voltage-controlled spin filtering systems using standard nonmagnetic semiconductor heterostructures.