Different Carrier Filling And Magnetic Field Conditions, Three Potential Barrier / Double-well Heterostructure Spectroscopic Properties And Tunneling Characteristics Of Study

With the continuous development of low-dimensional semiconductor physics, people have paid more and more attention on the exploration of the devices based on low-dimensional semiconductor structures. That, in return, motivates that many new progresses of fundamental research in this field have been achieved continually. Nowadays, the optical properties of quantum wells(QW) fabricated by different materials and structures and the influences of various external conditions such as electric field, magnetic field , pressure and temperature etc have been studied in detail. Among them, modulation-doping was also used to inject a certain quantity of excess electrons or holes into QW in order to see how it affects the optical properties. Under this condition, once the structures were determined, it became difficult to vary the density of excess carriers of the QW in situ.In this thesis, by continuously changing an external electric field across a specially-designed three-barrier-double-well tunneling structure, the density of excess electrons in the QW can be turned in a controllable manner. At high bias, electron- injecting from the emitter was used to adjust and control the filling of electrons in different subbands in combination of its escaping through a resonant-tunneling structure. It was observed that the occupation in first-excited electron state can result in a suppression to Quantum Confinement Stark Effect (QCSE). Obviously, this phenomenon results from different spatial characters of wave functions in the ground and first excited states. Moreover, at very low bias, a series of intrigue photoluminescence peaks shows up as the electrons are gradually filled into the ground state of the quantum well. It is verified that these new PL peaks can't be explained by the theory of band-to-band transition in the framework of single electron picture. Accordingly, our observation implies that more deep physical insight has to be explored.We also study the current-voltage characteristics and the photoluminescence spectra of our sample in a conjugated manner with the emphasis on the mechanism of the magnetic suppression of the resonant-tunneling current peak. Compared with ourprevious work, it is found that the potential feedback, possessed by the very peculiarly designed sample structure, also play an important role in addition to the magnetic-field induced slowdown of intersubband relaxation rate. That may give an explanation of why such suppression of the tunneling current peak is so sensitive to the structure parameters of the samples.In summary, through this thesis work, it was in details studied that the influence of level filling on optical properties of quantum well in both electric field and magnetic field. It is also explored that the physical origin about the suppression of resonant-tunneling current by a perpendicular magnetic field.