## 3 Results and Discussion
:  
\[\eta_{y}(\alpha)=-\,\eta_{y}(-\alpha). \tag{3}\]  
Meanwhile, the measured dependence of the transverse photocurrent on the polarization azimuth \(\Phi\) at a fixed \(\alpha=43.5^{\circ}\) (see Figure 2b) is approximated by an odd function:  
\[\eta_{y}(\alpha=43.5^{\circ},\Phi)=\eta_{y}(\alpha=43.5^{\circ},\Phi=45^{ \circ})\sin 2\Phi, \tag{4}\]  
where \(\eta_{y}(\alpha=43.5^{\circ},\Phi=45^{\circ})\) is the conversion coefficient of light into transverse photocurrent at \(\alpha=43.5^{\circ}\) and \(\Phi=45^{\circ}\). The set of angular and polarization dependences described by Equations (1)-(4) shown in Figures 1 and 2 indicates that the generation of photocurrent in the studied CuSe/\(t\)-Se thin films occurs according to the SPGE mechanism [5, 39, 40, 65]. Figure 2: The light to transverse photocurrent conversion coefficient \(\eta_{y}\) as a function of (**a**) the incidence angle \(\alpha\) at the polarization azimuth \(\Phi=-45^{\circ}\) (triangles correspond to the experimental data while the solid line represents the result of the fitting with equation \(\eta_{y}=8.37\sin 2\alpha/(0.87\cos\alpha+1)^{2}\)) and (**b**) the polarization azimuth \(\Phi\) at \(\alpha=43.5^{\circ}\) (circles denote experimental data, the solid curve represents the fitting with the equation \(\eta_{y}=-3.1\sin 2\,\Phi\); the orientations of the plane of polarization of the incident radiation are shown at the top). The insets show the sketches of the experimental setups. Figure 3a shows the unipolar pulse waveforms of the longitudinal photovoltage (measured in the geometry of the experiment when the measuring electrodes are oriented perpendicular to the plane of incidence), normalized to their extreme values at \(p\)-polarization of the incident radiation at \(\alpha=\pm 45^{\circ}\) and \(\alpha=\pm 78^{\circ}\). It follows that when the sign of the incidence angle is changed, the pulses are inverted, which is in agreement with Equation (1). It can also be seen that the waveforms of the pulses are virtually independent of the angle of incidence. This is evidenced by the dependence curve of the pulse duration \(\tau\) (FWHM) on \(\alpha\), presented in the inset to Figure 3a. Similar patterns were obtained when the longitudinal photovoltage was excited by circularly polarized radiation pulses (see Figure 3b). Thus, the waveforms of the longitudinal photovoltage pulses in the films under study for linear and circular polarizations are virtually independent from the angle of incidence. Figure 3: The waveforms of the longitudinal photovoltage pulses normalized to their extreme values at (**a**) linear polarization (\(\Phi=0\), \(p\)-polarization) and (**b**) circular polarization recorded at positive (solid lines) and negative (dashed lines) incidence angles \(\alpha\). The upper insets show the corresponding dependences of the recorded pulse durations \(\tau\) on the angle of incidence. The bottom insets show the sketches of the experimental setups. The waveforms of the transverse photovoltage pulses recorded at linear polarization (\(\Phi=-45^{\circ}\)) and normalized to their extreme values at different \(\alpha\) are shown in Figure 4. It can be seen that the waveforms of these pulses weakly depend on \(\alpha\). This is evidenced by the dependence of the pulse duration on the incidence angle, shown in the inset in the same figure. Figure 5 shows the waveforms of the transverse photovoltage pulses recorded for the right-hand circularly polarized laser beam at various angles of incidence. The pulses are normalized to their extreme values. It can be seen that at 0 \(<\alpha<\) 58.5\({}^{\circ}\), positive pulses are generated, the duration of which gradually increases with increasing \(\alpha\). In the range of angles \(\alpha\) approximately 58.5 \(\leq\alpha\leq\) 76.5\({}^{\circ}\) bipolar pulses are excited. Figure 5 shows that at \(\alpha=\) 58.5\({}^{\circ}\), a small negative pulse appears on the leading edge of the positive pulse.