# Spin-Related Micro-Photoluminescence in Fe\({}^{3+}\) Doped ZnSe Nanoribbons
## 3 Results and Discussion  
The morphology of as-synthesized Fe doped ZnSe nanoribbons is shown in Figure 1a. The nanoribbons are obtained in a large yield with a length of about 100-200 \(\upmu\)m and a width of about 10 \(\upmu\)m. Figure 1b shows an SEM image of an individual Fe doped ZnSe nanoribbon. Noticeably, the surface of the nanoribbon is clean and smooth. To confirm their elemental composition, EDS and EDS elemental mapping have been carried out. Figure 1c,d confirm the presence of three elements--Zn, Se, and Fe--illustrating that Fe ions are successfully doped into ZnSe nanoribbon relatively uniformly with an Fe atomic percent of about 0.68%. Figure 2 shows an XRD pattern and micro-Raman spectrum of Fe doped ZnSe nanoribbons. The red curve in Figure 2a is an XRD pattern of as-synthesized Fe doped ZnSe nanoribbons, in which all of the diffraction peaks are in good agreement with standard values as listed in the Joint Committee on Powder Diffraction Standards (JCPDS) card of No. 37-1463 shown by the black line of Figure 2a. Specifically, the peak at 38\({}^{\circ}\) is attributed to the diffraction peak of wurtzite ZnSe, which might come from some ZnSe particles on the thematic substrate. The strong diffraction peaks of the XRD pattern illustrate that the synthesized ZnSe nanoribbons are a zinc-blend structure and grow alone in the (111) crystal faces. Low concentration of Fe content leads to no other impurity or the secondary  
Figure 1: (**a**) Scanning electron microscopy (SEM) image of as-prepared Fe doped ZnSe nanoribbons; (**b**) SEM image of an individual Fe doped ZnSe nanoribbon; (**c**) Energy dispersive spectroscopy (EDS) elemental mapping of detecting three elements Zn, Se, and Fe, respectively; and the (**d**) EDS profile of a point of Fe doped ZnSe nanoribbon of (**c**). The inset is elemental content of the three elements of Fe doped ZnSe nanoribbon. phase, as shown in the inset of Figures 1d and 2a. Figure 2b shows the micro-Raman spectrum of an individual Fe doped ZnSe nanoribbon at room temperature measured by CW 532 nm laser exciting. The peaks at 143, 207, and 254 cm\({}^{-1}\) correspond to the zinc-blend ZnSe two transverse acoustic (2 TA) phonon modes [24], transverse optical (TO) phonon modes, and longitudinal optical (LO) phonon modes [25], respectively. The peak at 308 cm\({}^{-1}\) is assigned to the superposition of LO and TA phonon modes, which is related to the defect state in the ZnSe lattice [26]. The strong and sharp peaks in the Raman spectrum demonstrate the crystalline nature of Fe doped ZnSe nanoribbons well. In order to study the elementary excitations of Fe doped ZnSe nanoribbon, excited power-dependent PL spectra for one nanoribbon have been measured. Figure 3a shows its PL spectrum and optical morphology image of the nanoribbon in a dark field by 405 nm laser exciting. When a laser excites the nanoribbon, their endpoints emit yellow light, demonstrating that it has excellent optical waveguide properties, as shown in the inset of Figure 3a. In its PL spectrum, there are three emission peaks at 467, 553 and 630 nm, respectively. The first emission peak at 467 nm is assigned to near band-edge exciton emissions, whose nature needs further identification for the bandgap of pure ZnSe material is at about 2.7 eV (460 nm) at room temperature [27]. The second (D1) and third (D2) emission peak at 553 and 630 nm are related to Fe\({}^{3+}\)\(d\)-\(d\) transition, which will be discussed later. Figure 3b shows power-dependent PL spectra from 3 to 15 mW, in which the emission peak of near band edge shifts to long wavelengths with excited power increasing. To study the origin and the redshift of near band-edge emission, the emission fitting curves have been obtained, as shown in Figure 3c. The black curve is the experimental line measured at \(P\) = 15 mW, which can be fitted by three Gaussian functions, denoted as GFC1 (473 nm), GFC2 (485 nm), and GFC3 (492 nm), respectively.