Contactless electroreflectance of GaInNAsSb/GaNAs/GaAs quantum wells emitting at 1.5–1.65 μm: Broadening of the fundamental transition

Abstract

Contactless electroreflectance ͑CER͒ has been applied to study the broadening of the fundamental transition for GaInNAsSb/GaNAs/GaAs quantum wells ͑QWs͒ obtained at various growth and annealing conditions. It has been observed that CER resonances are about 50% narrower for QWs grown at lower group V fluxes and annealed at lower temperatures ͑660-720°C͒ and longer time ͑30-60 min͒ than those previously considered optimal ͑ϳ760°C and ϳ60 s͒. The long annealing can be partially realized in situ during ͑and/or after͒ the growth of the upper part of the laser structure instead the ex situ short-time annealing, where the laser structure can unintentionally be overannealed very easily.

Contactless electroreflectance spectroscopy of optical transitions in low dimensional semiconductor structures

“…The application of CER spectroscopy to study low dimen− sional heterostructures allows to investigate various mate− rial issues like (i) the built−in electric field including the Fermi−level position [7][8][9][10]15], (ii) the band−offset at semi− conductor interfaces [11][12][13][14], (iii) the homogeneity of low dimensional systems [16], (iv) the carrier localization effect including the Stokes shift [17], as well as other issues/ effects [18]. Some examples of the application of CER spec− troscopy to study selected material systems/heterostructures are presented below.…”

“…In general, the classical approach to measure electro−modulation spectra (including the CER ones) is the dark configuration [1][2][3][4] where the sample is illuminated with monochromatic light. Recently, the "bright" configuration is widely applied to measure PR and CER spectra [10][11][12][13][14][15][16][17][18]29,30]. In this review paper this experimental configuration is described and ap− plied to study optical properties of low dimensional semi− conductor structures.…”

“…For these purposes the QW width and alloy content have to be determined very carefully for the investigated samples using structural methods like X−ray diffractions and/or the cross section transmission electron microscopy. In addition, broadenings of CER resonances are very sensitive to the structural quality of the investigated QWs, i.e., the roughness of QW interfaces and alloy content inhomogeneities [16,17]. In this part we focus on the appli− cation of CER spectroscopy in order to study the number of confined states in QWs and band gap discontinuities at QW interfaces.…”

Time-resolved photoluminescence studies of annealed 1.3-μm GaInNAsSb quantum wells

“…Using GaInNAsSb quantum wells (QWs), lasers and vertical-cavity surface-emitting lasers operating at 1.3 μm [ 12 ] and 1.55 μm [ 13 , 14 ] have been demonstrated. However, the quality of an as-grown GaInNAsSb material can still be improved by post-growth annealing [ 15 , 16 ]. The effects of annealing on the optical properties of GaInNAsSb QWs have been studied in detail (see, for example, [ 13 ] and references therein).…”