无杂质空位扩散法造成InGaAsP/InP多量子阱结构带隙蓝移规律的研究

采用光荧光谱(PL)和光调制反射谱(PR)的方法,研究了由Si₃N₄、SiO₂电介质盖层引起的无杂质空位(IFVD)诱导的InGaAsP四元化合物半导体多量子阱(MQWs)结构的带隙蓝移。实验中Si₃N₄、SiO₂作为电介质盖层,用来产生空位,再经过快速热退火处理(RTA)。实验结果表明:多量子阱结构带隙蓝移和退火温度、复合盖层的组合有关。带隙蓝移随退火温度的升高而加大。InP、Si₃N₄复合盖层产生的带隙蓝移量大于InP、SiO₂复合盖层。而InGaAs、SiO₂复合盖层产生的带隙蓝移量则大于InGaAs、Si₃N₄复合盖层。同时,光调制反射谱的测试结果与光荧光测试的结果基本一致,因此,PR谱是用于测试带隙变化的另一种方法。

Band Gap Blue Shift of InGaAsP/InP MQWs By Impurity-Free Vacancy Disordering

The band gap tuning of multiple quantum wells (MQWs) structure in the compound semiconductor is becoming an important tool in fabricating optoelectronic devices.Especially,phonic integrated devices based on InGaAsP multiple quantum wells structure are particular imporance because of its dramatic increase in demand for long wavelength optical communication.To integrate several optoelectronic devices on a single wafer,we must divide area with different optolectronic properties such as refractive index and absorption wavelength.Selective regrowth and selective area epitaxy are two possible techniques that can be used for this purpose.However,there is considerable interesting in post growth quantum well intermixing (QWI) technique which can be used to modify the geometry and composition of MQWs in selected regions. There are several quantum well intermixing (QWI) techniques that provide the localized formation of band gap shifted area.Among these QWI techniques,impurity free vacancy disordering (IFVD)is believed to be a promising technique without free carrier absorption and damage of crystal lattice. In this paper, band gap blue shift of InGaAsP/InP multiple quantum wells by IFVD was investigated using photoluminescence(PL) and photoreflectance(PR).Si₃N₄ and SiO₂ were used for the dielectric layer to create the vacancies.Then all samples were annealed by rapid thermal ananealing (RTA).The results indicate that band gap blue shift depends on the annealing temperature and time.Band gap blue shift increases with the annealing temperature and time but it tends to saturate when the annealing time attains certain extent.The SiO₂ capping was successfully used with InGaAs cladding layer to cause larger band tuning effect in the InGaAsP/InP MQWs material than Si₃N₄ used with InGaAs cladding layer.On the other hand, samples with Si₃N₄-InP cap layer combinations also show larger energy shifts than SiO₂-InP cap layer combinations.At the same time,the results of band gap blue shift measured by PR are basically consistent with the results from PL.So, photoreflectance(PR) is alternative method,which can be used to measure band gap blue shift.To our knowledge,no report was concerned with measuring band gap blue shift using PR.Furthermore,the band gap blue shift affected by cap layer combinations created a new method for IFVD investigation. Sum up,this paper first reports the results of band gap blue shift measured by PR.To obtain large energy shift,the optimal selected cap layer combination is Si₃N₄-InP or SiO₂-InGaAs.