量子尺寸效应【quantum size effect】
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2013考研国家线预测>上海禽流感最新消息量子限制斯塔克【quantum-confined Stark effect (QCSE)】效应
receivedquantum size effect：
A double heterostructure is compod of a layer of lower bandgap material bound on both sides by layers of larger bandgap material . The carriers migrate to the energetically favorable positions inside the wells, where they are confined until recombination. Figure 4.1 depicts a typical double heterostructure commonly ud in nitride LED’s, in which the InGaN wells are bound on both sides by GaN barriers.初三英语教案
Once inside the wells, carriers act in accordance with the “particle-in-a-box” concept of quantum theory, which means that a ries of discrete energy states are formed within each well (e the dotted lines in the figure), as oppod to the energy continuum en in a bulk layer. Becau of the prence of the energy quanta, double heterostructures are commonly referred to as “quantum” wells. The quantized energy states within the well lead to an effective increa in the bandgap, and thus a blueshift of the emission energy.
This phenomenon is known as the quantum size effect and must be taken into account when analyzing the emission wavelength of an LED who active region is compod of quantum wells.我是剩女我怕谁
官瓷quantum-confined Stark effect (QCSE)：
When piezoelectric band-bending takes place, the conduction band minimum is shifted to a lower energy. The valence band maximum, however, remains energetically at the same location. Thus the effective bandgap of the material is lowered; i.e. emission will be redshifted.
男生英文名字大全This phenomenon is known as the quantum-confined Stark effect (QCSE)
