## 3 Results
Then, the satellite peaks also appear at \(\pm\) n \(\times\) 194 \(\mu\)V with n = 2, 3, 4 (light blue, navy, and purple curves). The separation of these satellite peaks from each other and the main one is a multiple of 194 \(\mu\)V. This value is equal to the value \(\rm hf/2e\) at a frequency \(f\) = 94 GHz, and not \(\rm hf/e\), as it could be if the cause of the formation of a feature in the \(I\)-\(V\) curve is the inelastic tunneling of quasiparticles [35]. Figure 4: Dependences of differential conductivities \(\rm dI/d\)\(V\) on voltage \(V\): (**a**) for two JJs of different widths \(w\) at temperature \(T\) = 5 K, where the insets show enlarged features at 7.4 and 11.8 mV for the JJ with \(w\) = 1.5 \(\mu\)m; (**b**) for the JJ with \(w\) = 1 \(\mu\)m at \(T\) of 5 K and 42 K. Sample yd501282 on a \(2\times 11.3^{\circ}\) bicrystal NdGaO\({}_{3}\) substrate. Thus, we can conclude that the features in the dc _I-V_ curves of JJs are associated with the interaction of Josephson oscillations with frequency-localized modes in these JJs themselves and the nearest environment. The relative modulation of the differential conductance \(R_{n}\Delta dI/\mathrm{d}V\) near the detected feature at voltages of about 9.4 mV reaches 80%, which means a significant mode intensity. The vibrational modes of separate organic molecules in tunneling barriers are usually weaker, with a relative conductance modulation of about 1% [28]. In connection with this circumstance, one should consider the frequencies of optical phonons or, more generally, collective modes in the JJ material itself, \(\mathrm{YBa_{2}Cu_{3}O_{7-x}}\). In this case, one should foresee that the oxygen concentration in the electrodes adjacent to the structural barrier of the JJ could decrease during the preparation of the JJ. This circumstance, in turn, can affect the position and shape of the features on the _I-V_ curve of the JJ. To elucidate the effect of oxygen on the voltage position of features on the _I-V_ curve, we measured several JJs as fabricated and after additional low-temperature annealing in atomic oxygen. Figure 6 presents the results, where the numbers on the curves correspond to the JJ numbers on the same substrate, and the letters \"b\" or \"a\" correspond to the junction state: b--before low-temperature annealing (before), a--after this annealing (after). As follows from Figure 6, annealing in atomic oxygen leads to a close to a twofold increase in the conductance \(1/R_{n}\) of the JJs, an enhancement of the features around 9.4 mV and 4.7 mV, and a weakening of those at around 7.4 mV and 5.6 mV. Figure 5: Modification of the differential conductance \(\mathrm{d}I/\mathrm{d}V\) on the voltage \(V\) of a JJ with mutually tilted _c_-axes (red curve) under electromagnetic irradiation with a frequency of \(f=94\) GHz with increasing power levels (curves from orange to purple). The vertical dashed lines are separated in voltage by \(\pm n\times\mathrm{b}f/2\mathrm{e}=194\)\(\mathrm{\SIUnitSymbolMicro V}\) (n = 1, 2, 3, 4) from the position of the peak at \(V=9.6\) mV on the unperturbed \(\mathrm{d}I/\mathrm{d}V\) versus \(V\). Sample yd501282 on a \(2\times 11.3^{\circ}\) NdGaO\({}_{3}\) substrate. \(T=5\) K.  
The features at voltages 11.8 and 12 mV are weaker and increase slightly after annealing. The most intensive peculiarity at voltages near 9.4 mV has an internal structure that is noticeable even in unannealed samples (curves 1b, 2b). Two peaks are visible, the first at 9.55 mV and the second at 9.65 mV. Adding the oxygen content to the JJ increases the peak at 9.65 mV absolutely and relative to the peak at 9.55 mV (curves 1a, 2a).