**3.1. Morphological and X-ray diffraction analysis**

**Figure 2a** and **b** shows the scanning electron microscopy (SEM) images of Ca0.5R1-*x*(MoO4)2:*x*Ln3+ (R3+ = Y, La), (Ln3+ = Eu, Tb, Dy) thin phosphor film co-doped with Li+ , K+ and Na+ metal ions prepared at 600°C with 300 mTorr. The as-prepared phosphor film comprises homogeneous nearly circular grains with a typical grain size around 250 nm. Based on the AFM studies, the surface topography, line profile and roughness of the prepared thin film was estimated. **Figures 3a** and **4a** show the 3D AFM image of thin film of Ca0.5R(MoO4)2:Eu3+ (R = Y, La), and the scan was performed on 3 × 3 and 5 × 5 µm2 area, respectively. From the 3D topographic image, the as-prepared thin phosphor film comprises of polished surface with uniform arrangement of the particles and with less agglomeration. The average roughness along with root-mean-square (rms) of the as-grown thin film was determined as 24.72 and 26.84 nm for Ca0.5R1-*x*(MoO4)2:*x*Eu3+ (R3+ = Y, La). The 3D surface topography, 2D surface scan image, line profile, and histogram analysis are shown in **Figures 3a**–**d** and **4a**–**d**, respectively. Based on the scaling process, the particle size would be reduced to nano-scale in thin film which could be efficiently used for display applications. The optimization of maintaining different substrate temperature on rare-earth doped phosphors has been well examined and reported in our earlier work [2].

**Figure 2.** The SEM image (a and b) of Ca0.5R0.5(MoO4)2:Eu3+ (R3+ = Y, La) thin film.

The crystallinity and phase purity of the prepared products were examined using indexed powder X-ray diffraction patterns **Figure 5(a** and **b)** for as grown thin film samples. The compound Ca0.5Y(1-*<sup>x</sup>*) (MoO4)2:*x*RE3+ crystallizes in the scheelite tetragonal crystal structure with a space group of I41/a. The unit cell of Ca0.5Y(1-*<sup>x</sup>*) (MoO4) 2 consists of [MoO4] 2- anions and Ca2+ and Y3+/La3+ cations. In this phase, Mo sites are occupied by the molybdenum atoms (Mo6+) and located at the centres of tetrahedron and surrounded by four equivalent oxygen (O2-) atoms. The divalent Ca2+ and trivalent Y3+/La3+ occupies the dodecahedral sites associated with the tetrahedral symmetry. The degree of dodecahedral and tetrahedral distortions is discussed in the previous work [2, 15, 17].

**Figure 3.** The AFM images of Ca0.5Y(MoO4)2:Eu3+ thin film (a) 3D surface topography, (b) 2D surface scan image, (c) line profile for vertical cross-section in 3 × 3 µm2 scan area and (d) histogram analysis.

In the powder XRD pattern, all the peaks are indexed perfectly which indicates a pure tetragonal phase having scheelite crystal structure and the planes (1 0 1), (1 1 2), (0 0 4), (2 0 0), (2 0 4), (2 2 0), (1 1 6) and (1 3 2) are in well accordance with the JCPDS card no. 82-2369 of NaY(MoO4)2. No deleterious phases are found. The peak shift is not noticed with respect to doping. An intense peak with plane (1 1 2) is found at 28.95° [2, 15, 17].

#### **3.2. Photoluminescence properties of laser-ablated thin phosphor films: Ca0.5R1-***x***(MoO4)2:***x***Ln3+,M+ (R = Y, La; Ln = Eu, Tb and Dy; M = Li, K and Na)**
