ELECTRICAL CHARACTERIZATION OF POROUS SILICON

摘要

Porous silicon was investigated by capacitance and current-voltage measurements on MIS devices. Four different substrates: 6-8 ohmcm (p-type), 5×10~(-3) -2×10~(-2) ohmem (p+-type), 6-10 ohmcm (n-type) and 10~(-2)- 3×10~(-2) ohmcm (n~+-type) are used as starting material. The samples were also plasma oxidized in a RIE equipment at the power P=1500 W in a pure oxygen discharge. Porous silicon (PS) formed from p and p~+-type substrates exhibits full and partial carrier depletion respectively. The plasma oxidized porous silicon (OPS) for PS substrates with porosity P<60% presents a stable surface with an uniform SiO_2 layer, while for PS substrates with P>60% this effect is made indistinct by a large number of cracks occuring on the surface after plasma oxidation due to the morphological structure.