At each point, we calculated several tens of current-voltage characteristics with their own set of photodiode parameters ( n, S, S r, R c). In order to avoid a large volume of calculations, we fixed the variable N (i.e., the doping amplitude in the front layer) at a number of points. The problem was solved by a nonlinear Levenberg–Marquardt method with randomly chosen initial values of the unknown variables. To determine these, we used a least squares approximation of the experimentally measured current-voltage characteristics of the S6337 photodiode by theoretical curves, obtained using the PC1D model with fixed values of the parameters H and L. Īfter specifying the external parameters q and η in the form of implicit functions of the photodiode characteristics, five parameters remain unknown, namely, n, N, S, S r, and R c. The parameters L and H of the Hamamatsu S1337 photodiode are identical with the values from. After processing the photographs for the Hamamatsu S6337 photodiode, we obtained values of L = (45 ± 2) nm and H = (302 ± 3) μm, while for the Hamamatsu S1337 we obtained L = (57 ± 2) nm and H = (300 ± 3) μm. At the same time, it is obvious that the linear dimensions of the dark region can be regarded as the characteristic depth L of the photodiode doping. However, in view of the specific features of the photographs obtained using the electron microscope, one cannot obtain the doping profile from this photograph, since the electron microscope signal is not proportional to the carrier density in the region being measured. 2, where one can clearly distinguish the region of structural changes close to the front surface of the photodiode, which naturally relate to the doping region of the semiconductor. An example of a photograph of the section of the S6337 photodiode under an electron microscope is shown in Fig. For this purpose, at the Institute of Optophysical Measurements, using a scanning electron microscope, we investigated transverse sections of the Hamamatsu S6337 and S1337 photodiodes.
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