Self-organized InAs quantum dashes grown on In0.53Ga0.23Al0.24As∕InP have been investigated by chemically sensitive scanning transmission electron microscopy. The quantum dashes, which consist of pure InAs, exhibit a triangular cross section. Most important, the quantum dash size depends linearly on the nominal InAs layer thickness and can be varied by a factor of 3 without changing the height∕width ratio. Thus, the emission wavelength can be controlled between 1.37 and 1.9μm without modifying shape and composition of the quantum dashes by adjusting a single growth parameter.

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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.

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