What I did for Ridge-wire laser project
| Ridge-shaped quantum wire (Ridge-wire) is formed via facet growth
on a patterned substrate by molecular beam
epitaxy. We can make very smooth one dimensional structures, since the ridge-wire is formed by natural migrations of atoms on facet surfaces. In addition, confinement energies of electrons and holes are much larger than T-wire structures. Optical characterization of the ridge-wire laser was my thesis subject in ISSP, Univ. of Tokyo. Power Point Presentation for my thesis (English). [10.0 MB] |
 |
1. Imaging measurements for investigating
the spectral origin
|
We achieve lasing from the ridge-wire laser, and investigate the spectral origin of
photoluminascence and lasing. |
 |
2. Top-view measurement for investigationg
the uniformity and carrier migraion
| We observe top-view images of photoluminescence
and lasing of Ridge-wire laser, and investigate
the uniformity. As a result we can understand the origin of each PL peak and lasing. [References] [1] S. Watanabe et al., Appl. Phys. Lett., 75, 2190(1999). [219 kB] PDF file of the APL article 75, 2190 (1998). |
 |
3. Temperature dependence of the lasing property
The temperature dependence of carrier migration in ridge QWR structures are studied by micro- and macro-photoluminescence measurements. Above T=40K, the large carrier diffusion length cause the carriers in the QWR region to flow away due to the strutcural inhomogeneity, and thus cause the higher threshold power for lasing. [References] [1] S. Watanabeet al., Proceedings of the Sixth international symposium on advanced physical fields (APF-6), pp. 376(2001). PDF file of the proceedings of APF-6. |
 |
4. Numerical calculation for the electronic
structures
We develope a method to express wavefunctions of hole states in QWR structures to show how envelope wavefunctions relate to polarization properties of emission/absorption. This method allows us to easily understand the corespondance between the envelope functions and the polarization-dependent transition matrix elements. [References] [1] S. Watanabeet al., Jpn. J. Appl. Phys. Part I, 41,5924-5936 (2002). PDF file of the JJAP article 41, 5924 (200) [787 kB]. |
 |
5. Plarization measurement
We study vertically polarized lasing and spontaneous emission in a ridge QWR laser. In particular, we find that most of emissions with energies near the band edge are vertically polarized. We make numerical calculation, and find that the different effective mass causes different shapes of wave functions between electrons and holes, which results in larger oscillator strength of vertically-polarized transition. [References] [1] S. Watanabeet al., to be published in Phys. Rev. B. [2] S. Watanabeet al., 26th International Conference on the Physics of Semiconductors (2002). PDF file of the PRB article [712 kB]. PDF file of the proceeding of ICPS 26 [651 kB]. |
 |