Abstract

Semiconductor quantum dot (QD) is a nanosize region, in which the quantum-confinement of electrons and holes occurs in all the three directions, and hence the energy spectrum is discrete. Although the use of QDs as an active region in diode lasers can significantly improve their operating characteristics, there are still certain limitations in “conventional” QD lasers, such as the temperature dependence of the threshold current and sublinearity of the light-current characteristic. To suppress the recombination outside QDs and thus to enhance the temperature-stability of the laser operation, the tunneling-injection of both electrons and holes into QDs was proposed.
In this work, the potential of a tunneling-injection QD laser is studied for high-power operation. In an ideal device, no out-tunneling of carriers from QDs into the opposite-to-the-injection side of the structure can occur, and hence, there can be no parasitic recombination outside QDs, and the light-current curve will be strictly linear. To describe a more practical situation, we extended our model by including the out-tunneling of carriers from QDs; we showed that, up to very high pump currents, the parasitic recombination rates outside QDs remain restricted and, correspondingly, the light-current characteristic remains virtually linear. The linearity of the light-current dependence is due to the fact that the current paths connecting the opposite sides of a tunneling-injecting structure lie entirely within zero-dimensional QDs.

 

Biography

Dae-Seob Han received his B.S. degree in MSE from Chungnam National University in 2000 and M.S. degree in MSE from Gwangju Institute of Science and Technology in 2005. He worked in electronic-packaging research center at Samsung Company for 3 years and in information electronic materials group at LG Company for 2 years. He is currently pursuing his Ph.D. degree under the direction of Prof. Asryan. His area of study is semiconductor light-emitting devices with a quantum-confined active region.