The dynamics of excitons and trions in resonant tunneling diodes (original) (raw)
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Microelectronics Journal, 2003
In this work we study the formation of neutral and negatively charged excitons in double barrier resonant tunnelling structures, by analyzing the dependence of photoluminescence emission on excitation intensity. At low excitation intensities, the negatively charged to neutral exciton intensity ratio depends linearly on the current, suggesting the validity of the concept of thermal equilibrium in these structures. At high excitation intensities, however, this model fails, and an abrupt transition occurs which is associated to the scattering between charged excitons and free carriers in the quantum well, which dissociates the trion. q
Kinetics of excitonic complexes on tunneling devices
Physical Review B, 2005
In this work we have investigated the effects of trion formation on the tunneling current from both experimental and theoretical viewpoints. We have measured the current-voltage characteristics and the quantum-well photoluminescence emission of GaAs-Ga 1−x Al x As n-i-n double barrier diodes. We have observed a preresonance shoulder in the current-voltage curve under high laser intensities associated with the formation of trions in the quantum well, which increase the number of free states in the resonant and excitonic levels, thus enhancing the tunneling mechanism. These excitonic complexes were detected through the photoluminescence spectra under bias. We have observed that the preresonance shoulder occurs under the same conditions for which a trion peak in the luminescence spectrum is present. This trion-assisted mechanism is terminated when neutral and charged excitons are dissociated either by thermal excitation or by scattering with free carriers in the quantum well. A phenomenological rate equation model has allowed us to confirm our assumptions on the effect of trion formation on the charge transport.
Transport via excitonic complexes in resonant tunneling structures
Materials Science and Engineering: B, 2004
In this work we study the formation of neutral and negatively charged excitons in double barrier diodes under bias, and how they contribute to transport. We observe a pre-resonance shoulder in the current-voltage curve, which is associated to trion-assisted tunneling of electrons. We analyze this phenomenon by measuring also the quantum-well photoluminescence emission. This trion-assisted mechanism is terminated when trion complexes are dissociated either by thermal excitation or by scattering with free carriers in the quantum well. A simple phenomenological rate equation model allows us confirming the hypothesis of charge transport via a trion state and the proposed methods of termination. # 2004 Published by Elsevier B.V.
Electron-photon interaction in resonant tunneling diodes
Europhysics Letters (epl), 1997
We develope a model to describe the transmission coefficient and tunneling current in the presence of photon-electron coupling in a resonant diode. Our model takes into account multiphoton processes as well as the transitions between electronic states with different wave numbers. This is crutial to explain the experimental features observed in the tunneling current through a double barrier which cannot be reproduced with more simplified established models. According to our results, what experiments show in the current density are quantum photon-assisted features coming from multiphoton transitions which are not related with sample heating.
Quantum resonant tunneling in semiconductor double-barrier structure
Optik, 2018
Using Schrodinger equation, we have theoretically studied the quantum transport in double-barrier potential resonant tunneling diodes. To obtain higher peak in transmission coefficient in twofold barrier quantum well system require to reducing the barrier height and increasing the width of the quantum well which causes the electrons to turn unbounded. In addition, the potential energies should be below the height of the barrier. This occurs because on resonance with unity transmission requires exact cancellation in amplitude and phase of a coherent superposition of all contributions to the back-scattered particle-waves. At a certain height, width and potential energy, the resonances sit-down between barriers giving rise to peaks in transmission. Our model can be extended for several barriers to increasing the resonance peaks of transmission.
A quantum kinetic approach for modeling a two‐band resonant tunneling diode
Transport Theory and Statistical Physics, 2007
We present a mathematical study of a two-band quantum kinetic transport model. The multiband model, derived in the "kp" formalism, is designed to describe the dynamics in semiconductor devices when interband conduction-valence transition cannot be neglected. The Wigner formulation consists of a four-by-four system, containing two effective mass Wigner equations (one for the electron in conduction band and one for the valence band) coupled by pseudo-differential operators arising from the electric field in the semiconductor. Existence and uniqueness of a solution to the initial value problem are proved in a L 2 -setting for sufficiently regular electric potentials. An extension of the single band splitting-scheme algorithm is presented to solve the one-dimensional system for a bounded domain. Finally, we show some numerical result concerning the simulation of an interband resonant diode.
Semiconductors, 2007
Contactless optical electroreflectance measurements at different temperatures are used to study exciton states in a structure involving a periodic system of 36 GaAs quantum wells separated by tunneling-nontransparent AlGaAs barriers with thickness 104 nm. In the structure, the width of 32 of the quantum wells is 15 nm, while the width of the remaining four quantum wells, numbered 5, 14, 23, and 32, is 20 nm. The periodicity of the structure corresponds to the Bragg interference condition at the excitonic frequency in quantum wells at the angle of incidence of light ~43 °. From the quantitative analysis of the shape of the contactless electroreflectance line, the parameters of the exciton ground states and excited states are determined for both types of quantum wells. It is established that, for the system of four 20-nm-wide quantum wells separated by a distance of 830 nm, the size-quantization energy in the ground state is 8.4 ± 0.1 meV, and the parameter of broadening of the excitonic peak is 1.8 ± 0.1 meV at 17 K and increases with temperature up to 2.0 ± 0.1 meV at 80 K. For the system of 32 wells with the width 15 nm, the quantum confinement energy in the ground state is 14.9 ± 0.1 meV, and the parameter of broadening of the excitonic peak is 2.2 ± 0.1 and 2.6 ± 0.1 meV at 17 and 80 K, respectively. The possible causes of radiative and nonradiative broadening of exciton states in the systems are discussed.
Negative charged excitons in double barrier diodes
Microelectronics Journal, 2005
We have studied the effects of excitonic complexes formation, such as excitons and trions, on the optical and on transport properties of GaAs-GaAlAs n-i-n double barrier diodes, by measuring the current-voltage characteristics and the photoluminescence emission, as function of bias. The observation of a pre-resonance shoulder in the I(V) curves, under high laser intensities, and a negative charged excitons in the photoluminescence spectra, under the same bias conditions, were associated to the dissociation of these complexes either by thermal excitation or by scattering with 'free' carriers in the quantum well layer. A simple rate equation model allows us to explain the kinetics of the excitonic complexes in double barrier devices. q
Electroluminescence and multiphoton effects in a resonator driven by a tunnel junction
Physical Review B, 2015
We consider a transmission line resonator which is driven by electrons tunneling through a voltagebiased tunnel junction. Using the Born-Markovian quantum master equation in the polaron basis we investigate the nonequilibrium photon state and emission spectrum of the resonator as well as properties of the transport current across the tunnel junction and its noise spectrum. The electroluminescence is optimized, with maximum peak height and narrow linewidth, when the backaction of the tunnel junction on the resonator and the decay rate of the resonator are similar in strength. For strong coupling between the resonator and tunnel junction, multi-photon effects show up in the noise spectrum of the transport current.