Fig. 1. (Color online) Fabrication scheme of SBT 5J cells. The arrow indicates the bonding interface.

Fig. 2. (Color online) Predicted efficiencies of T3Js containing a GaAs subcell (a) without and (b) with LC. LC coefficient is set to 0.93 during calculation.

Fig. 3. (Color online) Calculated band diagram for 2.10/1.72/1.42 eV T3J.

Fig. 4. Spinodal isotherms for InGaAsP quaternary. The thick solid line indicates compositions lattice-matched to InP.

Fig. 5. (Color online) Band profile of (a) AlGaInP/AlGaAs tunnel diode, and (b) electrical field and (c, d) tunneling probability distribution in the junction.

Fig. 6. (Color online) Schematic device structure after the bonding process.

Fig. 7. (Color online) Measured surface reflection and its fitting results.

Fig. 8. (Color online)J–V curves for the representative subcells ((a)12-cm² T3J cell, (b) 4-cm² B2J cell), and (c) J–V curve and (d) corrected QE for the best representative 4-cm² SBT 5J cell.