Molecular Beam Epitaxy Growth of CdSe for Si-based Tandem Cell Application

Stephen Schaefer, Zheng Ju, Allison McMinn, Xin Qi, Yong Hang Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The II-VI compound semiconductor CdSe has a bandgap energy of 1.71 eV [1] and 1.68 eV [2] in the wurtzite (hexagonal) and zincblende (cubic) crystal structures, respectively, making it an ideal candidate material for the top cell in tandem application with a Si bottom cell. However, the growth of monocrystalline CdSe and control of its phase, wurtzite or zincblende, remains a challenge. Molecular beam epitaxy (MBE) growth of CdSe thin films nearly lattice matched to InAs (100), (111)A, and (111)B oriented substrates is investigated. Growth temperature ranges from 250 to 350 °C, Cd/Se flux ratio ranges from 0.74 to 1.35, and the growth rate ranges from 0.14 to 0.84 monolayers per second. Single crystal zincblende material luminescing at 1.668 eV is demonstrated on the (100) substrates, while polycrystalline mixed-phase material luminescing from 1.589 to 1.726 eV is demonstrated on the (111) substrates. In-situ reflection high energy electron diffraction (RHEED) patterns show a clear transition from zincblende 1 times 1 surface reconstructions with four-fold symmetry to wurtzite 1 times 1 reconstructions with six-fold symmetry. The results indicate that CdSe crystal phase and thin film morphology is highly sensitive to growth temperature, Cd/Se flux ratio, and polar (111) surface preparation.

Original languageEnglish (US)
Title of host publication2022 IEEE 49th Photovoltaics Specialists Conference, PVSC 2022
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages3
ISBN (Electronic)9781728161174
StatePublished - 2022
Event49th IEEE Photovoltaics Specialists Conference, PVSC 2022 - Philadelphia, United States
Duration: Jun 5 2022Jun 10 2022

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Conference49th IEEE Photovoltaics Specialists Conference, PVSC 2022
Country/TerritoryUnited States


  • CdSe
  • II-VI
  • molecular beam epitaxy
  • photovoltaic
  • tandem cell
  • thin film

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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