Alternating current surface photovoltage in thermally oxidized chromium-contaminated n-type silicon wafers

作者：Shimizu Hirofumi^*; Nagase Shintarou; Ikeda Masanori

来源：Applied Physics A-Materials Science & Processing, 2011, 104(3): 929-934.

DOI：10.1007/s00339-011-6441-x

We investigated a variation of frequency-dependent alternating current (AC) surface photovoltages (SPVs) in thermally oxidized, chromium-contaminated, n-type silicon (Si) wafers. As previously reported, immediately after rinsing in Cr-contaminated solution, a Cr(OH)(3)-Si contact causes a Schottky-barrier-type AC SPV on n-type Si. Upon oxidation at 373 K for 10 min, the Schottky barrier collapses and, with further oxidation, a metal-induced negative oxide charge, due to atomic bridging of (CrOSi)(-) and/or CrO2- networks, definitely grows over time in SiO2. For samples oxidized at temperatures between 823 and 1023 K for 30 min, the observed AC SPV gives evidence that the metal-induced negative oxide charge causes a strongly inverted state of the Si surface. At oxidation temperatures higher than 1023 K and/or for an oxidation time longer than 60 min, the level height of the AC SPV is reduced, implying that the strongly inverted state changes into a less depleted state, whilst, finally, the AC SPV disappears. In this case, the collapse of the (CrOSi)(-) and/or CrO2- networks is anticipated, with a possible change into Cr2O3. The existence of the (CrOSi)(-) and/or CrO2- networks has also been confirmed in p-type Si wafers.

• 出版日期2011-9