Jpn. J. Appl. Phys. 35 (1996) pp. 1311-1319  |Next Article|  |Table of Contents|
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InAs–GaAs Quantum Pyramid Lasers: In Situ Growth, Radiative Lifetimes and Polarization Properties

D. Bimberg, N. N. Ledentsov, M. Grundmann, N. Kirstaedter, O. G. Schmidt, M. H. Mao, V. M. Ustinov¹, A. Yu. Egorov¹, A. E. Zhukov¹, P. S. Kopév¹, Zh. I. Alferov¹, S. S. Ruvimov², U. Gösele² and J. Heydenreich²

(Received October 23, 1995; accepted for publication November 21, 1995)

We have realized injection lasers based on InAs–GaAs and InGaAs–GaAs quantum pyramids (QPs) with a lateral size ranging from 80 to 140 Å. The structures with relatively small dots (∼80 Å) exhibit properties predicted earlier for quantum dot (QD) lasers such as low threshold current densities (below 100 Acm^-2) and ultrahigh characteristic temperatures (T₀=350–425 K). For operation temperatures above 100–130 K, T₀ decreases and the threshold current density increases (up to 0.95–3.3 kAcm^-2 at room temperature) due to carrier evaporation from QPs. Larger InAs QPs (∼140 Å) providing better carrier localization exhibit saturation of the ground-state emission and enhanced nonradiative recombination rate at high excitation densities. The radiative lifetime shows a weak dependence on the dot size in the range 80–140 Å being close to ∼1.8–2 ns, respectively. A significant decrease in radiative lifetime is realized in vertically coupled quantum dots formed by a QP shape-transformation effect. The final arrangement corresponds to a three-dimensional tetragonal array of InAs islands inserted in a GaAs matrix each composed of several vertically merging InAs parts. We achieved injection lasing in such an array for the first time.

URL: http://jjap.jsap.jp/link?JJAP/35/1311/
DOI: 10.1143/JJAP.35.1311

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