InSb quantum dots and quantum rings in a narrow-gap InAsSbP matrix

Abstract

We report a study of InSb quantum dots and quantum rings grown on InAs(100) substrate by LPE-MOVPE combine method. Characterization of InSb/InAs(Sb,P) quantum dots was performed using atomic force microscopy and transmission electron microscopy. The bimodal growth of uncapped InSb quantum dots was observed in the temperature range T=420-450 °C. The low-density (5×10⁸ cm^-2) large quantum dots with dimensions of 12-14 nm in height and 45-50 nm in diameter are appeared at 445 °C, whereas high-density (1×10¹⁰ cm^-2) dislocation-free small quantum dots with dimensions of 3-5 nm in height and 11-13 nm in diameter were obtained at 430 °C. Capping of the InSb quantum dots by binary InAs or InAsSbP epilayers lattice-matched with InAs substrate was performed using MOVPE method. Tunnel-related behavior in a forward curve of I-V characteristics was observed in heterostructures with buried InSb quantum dots inserted in InAs p-n junction. Evolution of electroluminescence spectra on driving current at negative bias and suppression of negative luminescence from buried InSb/InAs quantum dots were found out in the spectral range 3-4 μm at 300 K. Deposition from the InSb melt over the InAsSb_0.05P_0.10 capping layer resulted in the formation of InSb quantum rings with outer and inner diameters about 20-30 nm and 15-18 nm respectively. Surface density of the quantum rings of 2.6×10¹⁰ cm^-2 was reached at 430 °C.