GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates

Abstract

Large area, crack-free GaInP / GaAs double junction solar cells were grown by metal organic chemical vapor deposition on Ge/ Si templates fabricated using wafer bonding and ion implantation induced layer transfer. Photovoltaic performance of these devices was comparable to those grown on bulk epi-ready Ge, demonstrating the feasibility of alternative substrates fabricated via wafer bonding and layer transfer for growth of active devices on lattice mismatched substrates.

A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells: Multijunction Tandem, Lower Dimensional, Photonic Up/Down Conversion and Plasmonic Nanometallic Structures

“…47 As monolithic 2J cell with a lattice mismatch of 4% has been prepared, indicating potential for an InGaP/GaAs/InGaAsP/InGaAs 4J cell, as depicted in Figure 11, through bonding of an InGaP/GaAs 2J subcell and an InP-based 1eV-InGaAsP/0.73eV-InGaAs 2J subcell with the 4% lattice mismatch [60]. As a strategy to lower manufacturing costs by reusing expensive III-V semiconductor compound substrates, Ge/Si and InP/Si alternative growth substrates fabricated through wafer bonding and layer transfer of Ge and InP thin films onto Si substrates and growth of InGaP/GaAs 2J and InGaAs 1J cells on each with comparable cell efficiencies relative to cells grown on bulk Ge and InP substrates, respectively, have been demonstrated [61,62]. Tunnel junction…”

III–V Multijunction Solar Cell Integration with Silicon: Present Status, Challenges and Future Outlook

“…The bonded pair was then annealed to 250-350˚C under > 1 MPa pressure to enable hydrogen-induced layer splitting which initiates the propagation of microcracks parallel to the Ge surface upon annealing (Zahler et al 2002). Archer et al (2008) utilized such bonded templates fabricated with wafer bonding and ion-implantation induced layer transfer technique to realize 2J GaInP/GaAs solar cells (grown by MOVPE) on Ge/Si template with comparable performance to those grown on epi-ready Ge substrate. For the device grown on Ge/Si template, the J sc was comparable to the control samples on bulk Ge substrate, however the V oc was slightly lower (1.97-2.08 V vs 2.16 V).…”

“…The authors attributed the decrease in GaInP bandgap (for the samples grown on Ge/ Si template) as one of the main reasons for lower V oc . The decrease in GaInP bandgap was believed to be due to the difference in the Ge substrate miscut used to make the Ge/Si template (Archer et al 2008). It is not trivial to decouple the contributions from the substrate miscut, the GaInP ordering effect and due to the growth conditions on Ge vs Ge/Si substrates and warrants further investigation.…”

“…This approach is similar to the direct fusion bonding technique. One of the key advantages of this approach is the post-growth wafer bonding which to an extent circumvents the thermal stress caused by difference in thermal expansion coefficient between GaAs and Si, unlike the hydrogen-induced layer transfer technique to realize Ge on Si template (Archer et al 2008). The fast beam activated direct wafer bonding process was carried out in an Ayumi SAB-100 system.…”

III‐V Solar Cells

“…The most immediate technological goal is to bond a low-bandgap combination of InGaAsP/InGaAs grown on InP with the high-gap combination of InGaP/GaAs, resulting in a four-junctions solar cell [147]. To date, low-band-gap InGaAs solar cells grown on InP have been successfully transferred to Si substrates [148] and Ge layers have been bonded onto Si substrates followed by the growth of InGaP/GaAs multijunction solar cells on the Ge template [149].…”