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A wire-on-well (WoW) structure was fabricated using InGaAs/GaAs/GaAsP superlattice device growth technology. This structure modifies the local concentration of carriers in the quantum well and lengthens the carrier lifetime to increase carrier transport efficiency. However, the reason for this remains unclear. Therefore, we investigated the detailed carrier transition properties using photoluminescence (PL) and photoreflectance measurements. Regarding the PL spectra at 4 K, two characteristic peaks at 1.39 and 1.34 eV were observed. Both transitions are attributed to the recombination between the first quantum level of the electron (e1) and that of the heavy hole (hh1). We also discussed the carrier distribution in the WoW structure and found that the maximum carrier existing probabilities for e1 and hh1 are located at different positions. The less overlapping of the wavefunctions causes low transition probability and results in the observed long carrier lifetime. An additional prominent result in the WoW structure is the blue shift attributed to the 1.34 eV PL peak induced by increasing laser excitation power. We found that the blue shift occurred by the screening of the electric field caused by the compressive strain, as in the case of the quantum-confined Stark effect. [ABSTRACT FROM AUTHOR]

A method for measuring light absorption using photothermal deflection spectroscopy (PDS) is investigated. Typical reflectance and transmittance (R & T) absorption measurements have low spectral resolution (SR) with standard setups. It is believed that absorption measurements using PDS solve this problem because of its high sensitivity, even at a high SR. However, accurate absorption measurements have not been obtained using conventional PDS. The reflectance of the sample must be considered in the absorptance calculations. Various absorption measurement methods are compared and a novel calculation method for accurate PDS absorption measurements is proposed. A sample with quantum structures is fabricated and PDS measurements are performed. Exciton absorption peaks are also observed. The high SR of PDS is demonstrated and the measured exciton absorption peaks are confirmed using piezoelectric photothermal measurements. Furthermore, it is confirmed that the absolute values of absorptance derived from the R & T and PDS measurements agree well. The new PDS absorption measurement technique enables to obtain accurate absorption characteristics, which are indispensable for designing and optimizing optoelectronic devices. [ABSTRACT FROM AUTHOR]