## 1 Introduction  
Cadmium telluride (CdTe) is a group II-VI compound semiconductor with applications in both radiation detection and solar photovoltaic (PV) technology. Undoped CdTe single crystals typically exhibit p-type conductivity and low resistivity because of concentrations of native defects and impurities [1; 2]. To achieve the high resistivity (>10\({}^{9}\)\(\Omega\)cm) required for X-ray and gamma-ray detector fabrication, donor doping with group III and VII elements is commonly employed to compensate for these defects [2; 3; 4]. The most significant application of CdTe is as an active light-absorbing layer in high-efficiency solar cells. This is because of its optical absorption coefficient, which is greater than 10\({}^{4}\) cm\({}^{-1}\)[5]. As a result, it can absorb incident light with energy above its bandgap within 1 \(\upmu\)m from the surface. Consequently, CdTe cells require only 1 to 3 \(\upmu\)m thickness, contrary to traditional silicon cells that need 200 \(\upmu\)m of material [6]. This reduction in thickness significantly decreases the weight of CdTe cells and offers the potential for lower production costs. Several methods are used for the preparation of thin films of CdTe, such as chemical synthesis [7], spray pyrolysis [8], thermal evaporation [9], electrodeposition [10], sputtering [11], and molecular beam epitaxy [12]. To achieve high efficiency, optoelectronic devices, PV systems, surfaces, and interfaces must exhibit excellent crystalline quality. However, thin-film deposition methods employed in manufacturing often introduce surface irregularities. For instance, the use of textured substrates in solar cells frequently results in rough surfaces [13]. This roughness significantly affects solar cell efficiency, particularly for absorber material where light absorption is directly correlated with surface morphology. Moreover, surface roughness significantly influences the optical, electrical, and vibrational properties of semiconductor materials. Surface irregularities can scatter and absorb light, altering reflectivity and transmission, which are critical for optoelectronic devices' performance [14]. Additionally, surface roughness can introduce electronic states within the bandgap, acting as recombination centers that degrade carrier lifetimes and transport properties [15]. Furthermore, variations in atomic arrangement at the rough surface can disrupt phonon modes, leading to changes in vibrational spectra and thermal conductivity [16]. Therefore, precise control over surface morphology is essential for optimizing the performance of semiconductor-based technologies, making its study relevant to applied and basic science. Surface morphology is commonly investigated using atomic force microscopy (AFM), a scanning probe technique that generates a three-dimensional topography image of material surfaces at the nanometer scale [17]. Complementary to AFM, non-contact optical probes such as photoluminescence (PL) and Raman spectroscopy (RS) offer valuable insights into surface characteristics, including electronic states and vibrational modes. PL spectroscopy is a non-destructive technique that analyzes the emitted light from a material under optical excitation, providing information on its electronic structure. Room-temperature PL spectroscopy reveals both direct band-edge recombination and emission associated with deeper defect-related states. Spectral features, including intensity, peak position, and linewidth, correlate with crystal quality, energy levels, and surface roughness [18]. While PL spectroscopy offers static information about a material's electronic properties, time-resolved photoluminescence (TRPL) delves into the dynamic behavior of excited states. In a TRPL measurement, a material is photoexcited by a short (typically nanosecond) laser pulse, and the intensity of the emitted light is analyzed as a function of time [19]. TRPL complements PL spectroscopy by providing information on carrier lifetimes, recombination rates, and other time-dependent processes.