作者ghast319 (唉....)
看板Chemistry
标题Re: 关於semiconductor
时间Thu Feb 8 12:46:55 2007
※ 引述《patrickk (好难抉择)》之铭言:
: 急问加入TiO2的半导体是哪一型的
: 我猜是p-type
: 因为Ti+4没有价电子
: 不知道这样对不对??
: 说明一下这是研究所考题,原文如下
: What type of semiconductor is formed by increasing the amount of metal in
: TiO2?
※ 引述《patrickk (好难抉择)》之铭言:
: 急问加入TiO2的半导体是哪一型的
: 我猜是p-type
: 因为Ti+4没有价电子
: 不知道这样对不对??
: 说明一下这是研究所考题,原文如下
: What type of semiconductor is formed by increasing the amount of metal in
: TiO2?
Maybe we can discuss the question with the Co(2+)-doped TiO2 film.
In TiO2, titanium/oxygen bonds are primarily ionic, but slightly covalent.
Each titanium gives four electrons to oxygen neighbors and each oxygen atom
takes two electrons from titanim neighbors, but covalent character causes them
to share electrons. Moreover, each oxygen atom pulls two electrons from two
different titanium atoms, so from geometrical considerations we have reason to
believe that an oxygen vacancy adjacent to a cobalt atom should compensate for
only one electron charge at the cobalt site and leave an adjacent titanium
atom with an extra electron. In fact, these kind of oxygen vacancies material
can generate polarons(but not all), which may be mediating ferromagnetism, and
they generate charge carriers that make TiO2 an n-type semiconductor.
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