Luminescent Characteristics of InGaAsP/InP Multiple Quantum Well Structures by Impurity-Free Vacancy Disordering
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Luminescent Characteristics of InGaAsP/InP Multiple Quantum Well Structures by Impurity-Free Vacancy Disordering J. Zhao1 , X. D. Zhang1 , Z. C. Feng2,∗ , J. C. Deng1,3, P. Jin4 , Y. C. Wang1 , and G. Xu 5 1
Department of Physics & Institute of Materials Science, Tianjin Normal University, Tianjin 300074, P. R. China. 2 Axcel photonics, 45 Bartlett Street, Marlborough, MA 01752, USA 3 Department of Materials Science, National University of Singapore, 119260 Singapore 4 College of Physics, Nankai University, Tianjin 300074, P. R. China. 5 Department of Materials Sci. & Engineering, McMaster University, Hamilton, Canada L8S 4L7
ABSTRACT InGaAsP/InP multiple quantum wells have been prepared by Impurity-Free Vacancy Disordering (IFVD). The luminescent characteristics was investigated using photoluminescence (PL) and photoreflectance (PR), from which the band gap blue shift was observed. Si3 N4 , SiO 2 and SOG were used for the dielectric layer to create the vacancies. All samples were annealed by rapid thermal anne aling (RTA). The results indicate that the band gap blue shift varies with the dielectric layers and annealing temperature. The SiO 2 capping was successfully used with an InGaAs cladding layer to cause larger band tuning effect in the InGaAs/InP MQWs than the Si3 N4 capping with an InGaAs cladding layer. On the other hand, samples with the Si3 N4 -InP cap layer combination also show larger energy shifts than that with SiO 2 -InP cap layer combination.
INTRODUCTION In fabricating luminescent devices for integrated optoelectronic and photonic application, InGaAsP/InP multiple quantum well (MQW) structures have attracted research interests. Post-tuning of optical band gap energy can be achieved from these MQW structures, which posses the advantage to avoid the complicated post growth processing. Several technical approaches have been explored to achieve this purpose, including (1) Impurity Induced Disordering (IID) [1,2], (2) Implant Induced Composition Disordering (IICD) [3-6], and (3) Impurity-Free Vacancy Disordering (IFVD) [7,8]. Among them, IFVD technique shows more promising because it can keep high crystal quality and low optical propagation loses as well as it does not introduce free-carrier concentration. IFVD, utilizing a dielectric layer such as SiO 2 and Si3 N4 as Ga sink at elevated temperature, could result in the redistribution of Ga vacancies in MQWs to enhance the quantum well intermixing and thus to enhance the luminescence [9,10]. ∗
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I6.22.1
In this paper, a systematic investigation on luminescent characteristics of InGaAsP/InP MQW system using SiO 2 , Si3 N4 and SOG (spin on glass) as dielectric layers in IFVD is reported. Photoluminescence (PL) was measured by a Fourier Transform Infrared (FT-IR) PL system. Photoreflectance (PR) measurements on these samples were used to investigate further the behavior of band gap blue shift. To our knowledge, there was no report published with measuring band gap blue shift by PR for this material system yet.
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