Enhanced optical and electrical stability of thermally carbonized porous silicon

In the current paper, the intrinsic instability of physical properties of porous silicon (PS) was minimized using a thermal carbonization (TC) method. A typical PS showed an obvious quenching of its photoluminescence (PL) properties under long-term laser radiation. To resolve this problem, an ultra-thin stabilizing layer was grown on the porous structure under an acetylene gas flow. During the TC process at high temperatures, carbon atoms were detached from the acetylene molecules and dissolved in the porous structure. Thermally carbonized PS (TC-PS) layer changed the PL peak position of PS slightly due to the formation of Si–C species on porous surface after acetylene exposure. The effects of TC-PS layer in electrical properties of fabricated photodetectors were studied. The photocurrent of freshly prepared PS decreased under prolonged green laser radiation (532 nm, 5 mW), but the TC-PS sample showed more stable electrical characteristics under the same conditions.