Enhancement of band edge luminescence in ZnSe nanowires

Abstract

In order to realize the full potential of nanowires for optical applications, it is essential to synthesize nanowires that can emit predominantly via band to band or band edge (BE) transitions. However, many compound semiconductor nanowires, irrespective of the method of their growth, contain a high density of native defects; these result in competing deep defect (DD) related emission, limiting their utility for optoelectronic device applications. The concentration of these native defect states depends on the gas phase stoichiometry. In this work, we report on the influence of gas phase stoichiometry on the structural and optical properties of single crystal zinc selenide (ZnSe) nanowires. We find that nanowires grown under stoichiometric conditions contain such defect states with associated weak BE emission and strong DD emission. However, nanowires grown under Zn-rich conditions were characterized by photoluminescence spectra dominated by strong BE emission while those grown under Se-rich conditions showed strong DD related emission. Hence, it is necessary to develop a strategy for enhancing the BE emission while simultaneously quenching the DD emission. We demonstrate a technique of postgrowth treatment that can effectively perform this function, and using this strategy the ratio of the BE/DD emission can be increased by a factor of several thousands, at least an order of magnitude higher than previously reported values. This reveals BE dominated photoluminescence in these nanowires and makes these nanowires suitable for developing future optoelectronic devices.

Spin-Related Micro-Photoluminescence in Fe3+ Doped ZnSe Nanoribbons

“…Many works reported the defect-related emissions between 500 and 700 nm, such as point defect Zn vacancies, Zn interstitials, and structure defects dislocations, stacking faults and so on [35][36][37]. In the PL spectrum of Fe 3+ doped ZnSe nanoribbon, the narrow FWHM of D1 and D2 and the sharp near band-edge emission have eliminated the possibility of point defects for the latter often strongly relax the FX emission.…”

Photoluminescence of CdSe nanowires grown with and without metal catalyst

“…This, however, can hinder the extrapolation of representative features as structural inhomogeneities may be present. There have been a number of investigations of PL emission from individual Ⅱ-Ⅳ NWs, mostly at room-temperature (RT) [7,[23][24][25][26][27][28]. However, many radiative states have a binding energy lower than RT, and thus cannot be seen [7].…”

Ultrafast time-resolved spectroscopy of ZnSe nanowires: Carrier dynamics of defect-related states

“…The growth temperature for the sample was maintained at 650 • C. The nanowires have diameters in the range of 80-100 nm and lengths of 8-10 m. The nanowires were deposited on quartz substrates with a typical density of about 10 4 wires/mm 2 to perform the measurements reported in this work. Finally, we should point out that characterization of these samples can be found in detail elsewhere [5]. Photoluminescence measurements for the ZnSe nanowires grown under Se-rich and Zn-rich conditions are shown in Fig.…”

“…It was found that the presence of the broad low energy luminescence peak is attributed to intrinsic point defects of the ZnSe lattice [4]. Recently, there has been a significant development in band edge emission control in this material [5]. It was demonstrated that nanowires grown under Zn-rich conditions are dominated by strong band edge emission, while nanowires grown under Se-rich conditions have strong defect-related emission.…”