The electrochemical etching of porous silicon offers many diverse opportunities for production of complex porous silicon structures located not only on the surface but also in a bulk of the silicon devices. A specific technological regime, the photo-electrochemical etching can affect bulk of the silicon device but at the same time saving its textured surface almost unchanged. Our group is the first who investigated the silicon solar cells with textured surface modified by means of photo-electrochemical etching. Etched devices demonstrated better photoelectrical characteristics if compare ones with unmodified solar cells. Our current work presents results on research of solar cells photoelectrochemically treated in HF: ethanol solution. Applied etching regime allowed us to modify the emitter’s volume at the same time affecting only minimally the surface of the solar cell itself. SEM micrographs show the elevations, ripples, bumps, cracks etc. on the surface of photo-electrochemically treated solar cells. The optical ellipsometer spectra, optical microscope measurements results, SEM micrographs of surface morphology as well as light reflectivity of the photoelectrochemically treated and untreated surfaces of the solar cells investigated and discussed in this work.
Two-terminal diode-like porous silicon structures have been investigated under the impact of strong electric field. Strong
electric field I-V current-voltage characteristics have been measured in pulse regime by applying electric pulses of 15 ns
duration, at repetition rate of (100-150) Hz, creating average electric field in the structure up to (10<sup>3</sup>-10<sup>4</sup>) V/cm. Modification of structured state of the structures have been revealed at strong electric field influence, resulting in change
and stabilizing of their series resistance.
The new method based on the pulsed complex photomagnetoelectric (PME) effect has been proposed for generation of high frequency oscillations. The dynamics of PME photoresponse have been investigated experimentally in semiconductors InAs and Cd<sub>x</sub>Hg<sub>1-x</sub>Te (x=0.2 and 0.26) excited by Q-switched neodymium-YAG laser. The double sign inversion of the photoresponse signal was found at laser light flow I0 > 5 × 10<sup>24</sup> photons/cm<sup>2</sup>s in InAs and at I0 > 1-4 × 10<sup>24</sup> photons/cm<sup>2</sup>s in Cd<sub>x</sub>Hg<sub>1-x</sub>Te. Study of the frequency spectra of the doubly-sign-inversion signal of PME response applying DFT analysis reveal that, the spectra are broadened significantly in the region of high frequencies. The results exhibit the possibility to reach THz frequency range using laser pulses of the picosecond duration.