Emission Energy Shift in GaInAs/GaInAsP Strained Quantum-Box Structures Due to 0-Dimensional Quantum-Box Effect

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Abstract
We report, for the first time, the emission energy shift in GaInAs/GaInAsP quantum-box (QB) structures due to an obvious 0-dimensional quantum-box size effect. Ga1-xInxAs QBs withx=0.33 (tensile), 0.53 (unstrained), and 0.70 (compressive) were embedded in a GaInAsP (band-gap wavelength of 1.1 µm) optical absorption layer. These QB samples were fabricated by 2-step organometallic vapor-phase-epitaxy (OMVPE) growth, cross line lithography with electron-beam-exposure (EBX) direct writing, and the wet chemical etching process. The pitch of the QB array was 100 nm. The size of the boxes was controlled by changing the EB line dose, and measured by scanning electron microscope (SEM) to be 152–402nm2. Photoluminescence spectra at liquid helium temperature were measured. The emission peak of unstrained (US)-QB samples shifted from that of the reference quantum-film (QF) sample due to an obvious 0-dimensional quantum-size effect. This QB effect was investigated for US-, tensile (T)- and compressive-strained (CS)-QB structures systematically. Energy shift obtained for the CS-QB sample (ΔE=45–63 meV) is much larger than those for US-QB (9–19 meV) and TS-QB (19–23 meV) samples with the same box size (S=252nm2) by factors of 3–4 and 2–3 times, respectively. This is because of the reduction of the lateral hole effective mass in the compressive-strained case. From these results, we found that compressive-strained structure is expected to be more advantageous for low-threshold QB lasers.