Studies On Silicon-based Functional Films And Devices

Porous Silicon (PS) was considered to be a medium of special purpose due to its high porosity and extremely large internal surface area. It has been widely used in some fields. The structural and magnetic properties of Fe film based on PS have been studied in the first half of this paper. It has been proved that the coercivity of Fe thin films related with the surface roughness of PS, which was significant for magnetic recording and magnetic memory. A novel type of Si-based microcavity organic light-emitting diodes (MC-OLEDs) based on PS distributed Bragg reflectors (PS-DBR) were fabricated in the latter half of this paper. The difference between MC-OLEDs and Si-based OLEDS has been studied. The electroluminescent (EL) chromaticity of the cavity devices is highly enhanced, and the EL emission is in single mode with off-resonant optical modes highly suppressed. The I-B-V characteristics of the MC-OLEDs are similar to those of the conventional OLEDs; also the turn-on voltage and brightness are comparable to the conventional OLEDs.The mainly works are listed as following:The first half of this paper:1) PS was obtained with different porosities by anode electrochemical etching of boron-doped Silicon.2) The as-etched samples were then covered with Fe thin films by DC magnetron sputtering technique.3) Surface profile and structural investigation were studied with scanning tunneling microscopy (STM) and X-ray diffraction (XRD). Magneto-optical Kerr effect (MOKE) was employed to measure the hysteresis loops of the Fe films sputtered onto PS and the reference samples of Si substrate. The results obtained from comparing samples and theory investigating.The latter half of this paper:1) PS-DBR was formed by electrochemical pulsed anodic etching of Silicon substrates.2) SiO₂ as the electrical isolation layer between the anode and the cathode were deposited on PS-DBR by magnetron sputtering technique, and then ITO as the anode of OLEDs was deposited by changing the mask, too.3) Organic multilayer (CuPc/NPB/Alq₃ or Alq₃: DCJTB/Alq₃) /LiF/Al, electron-injection layer LiF, and the top mirror Ag were thermally deposited in a high vacuum system.4) Structural, optical, and electrical properties of MC-OLEDs and conventional OLEDs were compared and investigated in detail.The above two successful works are very valuable to study on Si-based functional films and light-emitting devices.