Voltage controlled electron spin dynamics in resonant tunnelling devices (original) (raw)
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Microelectronic Engineering, 1998
The tunnelling transport of electrons and holes is investigated in a double-barrier AlAs/GaAs resonant tunnelling light-emitting diode (RTLED) biased below flat band (≈1.5 V) using time-resolved photoluminescence (PL) spectroscopy. For photon energies above the confined exciton transition, a fast decaying PL component is observed which is ascribed to electron escape after e–h pair creation inside the well, with a characteristic time of 1 ns close to flat band and decreasing with electric field in the well. Below 1.1 V, photocarriers generated outside the well give rise to a slow decay component with characteristic times up to 3 ns, which is attributed to slow nonresonant tunnelling of electrons and holes from the respective depletion layers into the well. At lower external bias (higher field) the overall decay becomes faster due to faster hole tunnelling, as indicated by a qualitative change of the time dependence of the PL signal, and the relative growth of the light-hole exciton PL.
Voltage-controlled hole spin injection in nonmagnetic GaAs∕AlAs resonant tunneling structures
Physical Review B, 2006
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.
Spin injection in n-type resonant tunneling diodes
Nanoscale Research Letters, 2012
We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X − ). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to −88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers.
Journal of Physics D: Applied Physics, 2013
In this work, we have investigated the spin polarization from two-dimensional hole gases (2DHG) formed in p-i-p GaAs/AlAs resonant tunnelling diodes (RTDs) under magnetic field parallel to the tunnel current. We have observed that the polarization degree from the quantum well (QW) and the 2DHG formed at the accumulation layer is highly voltage and light sensitive and exhibits a clear sign inversion. Our results indicate that the voltage dependence of the QW polarization degree is mainly due to an efficient hole-resonant tunnelling process through spin states of the QW. On the other hand, the voltage dependence of the 2DHG polarization degree seems to be dependent on the hole density which is controlled by the applied voltage across the RTDs.
Light controlled spin polarization in asymmetric n-type resonant tunneling diode
Applied Physics Letters, 2007
The authors have observed a strong dependence of the circular polarization degree from the quantum well emission in an asymmetric n-type GaAs/ AlAs/ AlGaAs resonant tunneling diode on both the laser excitation intensity and the applied bias voltage. The sign of the circular polarization can be reversed by increasing the light excitation intensity when the structure is biased with voltages slightly larger than the first electron resonance. The variation of polarization is associated with a large density of photogenerated holes accumulated in the quantum well, which is enhanced due to the asymmetry of the structure.
Circular polarization in n-type resonant tunneling diodes with Si delta-doping in the quantum well
2014 29th Symposium on Microelectronics Technology and Devices (SBMicro), 2014
In this work, we have investigated magneto-transport and polarization resolved photoluminescence of a GaAs IAIGaAs resonant tunneling diode with Si delta-doping at the center of the quantum well under a magnetic field parallel to the tunnel current. Three resonant peaks were observed in the current-voltage characteristics curve (J(V)) which were associated to donor-assisted resonant tunneling, electron resonant tunneling and to phonon assisted resonant tunneling. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affect the spin-polarization of carriers in the well. The quantum well photoluminescence shows strong circular polarization degrees with values up to 85% under J 5T at the donor assisted resonant tunneling peak voltage. Our results can be exploited for fitture development of voltage-controlled spintronics devices.