采用分子束外延技术在(001)取向的InP衬底上外延生长了亚稳态的ZnxCd1-xSe/MgSe低维量子阱结构,并通过光致发光和子带吸收方法,分析其能带结构.在单量子阱样品制备过程中,高能电子衍射强度振荡表明MgSe可以实现二维生长模式,衍射图样证明其为亚稳态闪锌矿结构.通过引入厚的ZnxCd1-xSe空间层,抑制了MgSe垒层的相变,并能进一步提高样品的结晶质量,得到高结晶质量的多量子阱结构.通过计算不同阱宽的能带与光致发光实验比较,证明了ZnxCd1-xSe/MgSe的导带带阶为1.2 eV,价带带阶为0.27 eV.为了进一步验证其能带结构,制备了电子掺杂的ZnxCd1-xSe/MgSe的多量子阱,观测到半高宽很窄的中红外吸收.利用发光谱确定的带阶计算了量子阱中子带的吸收波长,和实验结果非常吻合.设计了一种双量子阱结构,计算结果显示,通过利用量子阱中的耦合效应,可以实现1.55.μm光通信波段的吸收.%We studied the band gap structure of ZnxCd1-xSe/MgSe heterostructure grown on (001) InP substrates by molecular beam epitaxy.In the single quantum well growth of Znx Cd1-xSe/MgSe,the in situ reflection high energy electron diffraction intensity oscillations and streak patterns demonstrate that zincblende (ZB) MgSe has been formed.Furthermore,with the introduction of thick Znx Cd1-xSe spacer layers,the ZB MgSe/ZnxCd1-xSe multi-quantum wells can be obtained.Based on the results of photoluminescence and calculation,the offset for conduction and valence band in MgSe/ZnxCd1-xSe heterostructure is estimated to be 1.2 eV and 0.27 eV,respectively.Using the estimated value of band offset,the calculated ISB transition energies agree well with results of infrared absorption experiments.With such a large band offset,ISB transitions in this material system could be extended to 1.55 μm within an asymmetric double quantum wells with coupling effects.
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