Contactless electroreflectance of InAs∕In0.53Ga0.23Al0.24As quantum dashes grown on InP substrate: Analysis of the wetting layer transition

Abstract

Articles you may be interested inContactless electroreflectance of optical transitions in tunnel-injection structures composed of an In 0.53 Ga 0.47 As / In 0.53 Ga 0.23 Al 0.24 As quantum well and InAs quantum dashes J. Appl. Phys. 108, 086106 (2010); 10.1063/1.3483948 Room temperature contactless electroreflectance of the ground and excited state transitions in Ga 0.76 In 0.24 As 0.08 Sb 0.92 ∕ Ga Sb single quantum wells of various widths Appl. Phys. Lett. 92, 041910 (2008); 10.1063/1.2840161 Band gap discontinuity in Ga 0.9 In 0.1 N 0.027 As 0.973 − x Sb x ∕ Ga As single quantum wells with 0 x 0.06 studied by contactless electroreflectance spectroscopy Appl. Phys. Lett. 88, 221113 (2006); 10.1063/1.2208949 Photoreflectance investigation of InAs quantum dashes embedded in In 0.53 Ga 0.47 As ∕ In 0.53 Ga 0.23 Al 0.24 As quantum well grown on InP substrateContactless electroreflectance ͑CER͒ spectroscopy has been applied to study optical transitions in InAs/ In 0.53 Ga 0.23 Al 0.24 As quantum dashes ͑QDashes͒ grown on an InP substrate by molecular beam epitaxy. CER resonances related to optical transitions in all relevant parts of the structure, i.e., InAs coverage, In 0.53 Ga 0.23 Al 0.24 As barriers, and the cap layer, have been clearly observed at room temperature. The signal, which is associated with light absorption in the InAs coverage, has been carefully analyzed, and the optical transitions in the wetting layer ͑WL͒ quantum well ͑QW͒ and QDashes have been identified in CER spectra. It has been shown that measurements of WL transitions and analysis of their energies allow us to determine the band gap discontinuity for the QDash/QDash-barrier interface. It has been found that the conduction band offset for the InAs/ In 0.53 Ga 0.23 Al 0.24 As interface is close to ϳ70%. Moreover, it has been observed that the intensity of the WL transition varies with the cap layer which was used to terminate the QDash structure. The conditions for the observation of WL transitions are discussed in this work.

Contactless electroreflectance spectroscopy of optical transitions in low dimensional semiconductor structures

“…It is worth noting that the same photon density applied to PL measurements of a QW allows to detect the fundamental transition only because of larger volume of QW in compari− son to the QD volume and faster carrier thermalization and recombination. CER spectroscopy due to their high sensiti− vity and absorption−like character is able to probe the each allowed optical transition in QDs as well as optical transi− tions in the wetting layer [48][49][50]. A few examples of the application of CER spectroscopy to study QD structures is presented below.…”

“…This resonance is associated with the photon absorption in InP cap/buffer layer. CER resonances related to the photon absorption in [50]. Figure 12 shows room temperature CER and PL spectra of an InAs QDash structure, see details of this structure in Ref.…”

“…In the first approximation, in order to estimate the number of optical transitions in InAs/Ga 0. 47 [50] and 60%, respectively [38]. Figure 15 shows energy levels and possible optical tran− sitions for the structure with 1.1−nm thick InAs layer.…”

“…50 and 59. Its thickness has been estimated to be about 0.7-1 nm, whereas the con− duction band offset for the InAs/Al 0.24 Ga 0.23 In 0.53 As inter− face is close to 70% [50]. In case of the T−I structures, it is expected that the addition of the potential associated with the InAs WL affects the energies and wave−functions of electrons and holes confined in the QW.…”

“…Figure 12 shows room temperature CER and PL spectra of an InAs QDash structure, see details of this structure in Ref. 50. CER signal related to photon absorption in InAs QDashes is observed at the energy of~0.75 eV.…”