AVS 60th International Symposium and Exhibition
    Electronic Materials and Processing Wednesday Sessions
       Session EM+AS+NS+SS-WeA

Invited Paper EM+AS+NS+SS-WeA7
Heteroepitaxial III-V/Si for Advanced Multijunction Photovoltaics

Wednesday, October 30, 2013, 4:00 pm, Room 102 A

Session: Semiconductor Heterostructures/Heusler Alloys
Presenter: S.A. Ringel, The Ohio State University
Authors: S.A. Ringel, The Ohio State University
T.J. Grassman, The Ohio State University
J.A. Carlin, The Ohio State University
C. Ratcliff, The Ohio State University
D. Chmielewski, The Ohio State University
Correspondent: Click to Email
The integration of III-V semiconductors with Si through epitaxial methods is receiving renewed interest, due to recent advances in mitigating defects related to the complex III-V/Si growth interface. In photovoltaics, a resultant III-V/Si heteroepitaxial solar cell would address the key technological barriers related to III-V solar cells, namely cost, manufacturing scalability and weight, and it would also address Si wafer photovoltaic concerns related to approaches that increase efficiencies of Si solar cells. This presentation will focus on our recent efforts regarding the achievement of high-quality, heterovalent epitaxy of GaP on (100)-oriented Si substrates in which all nucleation-driven defects have been eliminated. Device quality GaP/Si interfaces are an enabling pathway for the creation of III-V/Si multijunction photovoltaic devices in which the Si growth substrate can simultaneously act as a near-ideal sub-cell when epitaxially integrated beneath a metamorphic GaInP/GaAsP solar cell structure in which the GaInP, GaAsP and Si, having respective bandgap energies of ~ 2 ev/1.55 eV/1.1 eV, create a nearly ideal, Si-based, triple junction solar cell design. This presentation will focus on the heteroepitaxy of GaP/Si using both molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) methods. We have very recently transitioned our earlier MBE work on achieving nucleation-defect-free GaP/Si to the MOCVD environment (Grassman, et al., Applied Physics Letters 102, 142102, 2013)) and this presentation will focus on this MBE to MOCVD transition in which all such defects (anti-phase domains, stacking faults and microtwins) have been simultaneously and totally avoided. Four main topics will be presented: (1) GaP/Si(100) grown by MOCVD free of antiphase domains and stacking defects; (2) growth, fabrication, and testing of GaP/active-Si sub-cells utilizing the GaP as an effective passivation layer on Si sub-cells created by two methods - in-situ (i.e. in the III-V MOCVD growth system) and ex-situ (i.e. using high efficiency pre-processed Si sub-cells as growth substrates for III-V/GaP/Si integration); (3) MOCVD-grown GaAsP/Si multijunction structures having target lattice constants and bandgaps for high efficiency, and (4) comparative interface studies of nucleation-defect-free MBE- and MOCVD-grown III-V/GaP/Si. The presentation will capture the overall III-V/Si advances for multijunction III-V/active-Si photovoltaics.