Demonstration of nitride-on-phosphide hybrid tandem solar cells by using surface-activated bonding

Abstract

Group-III nitride-on-phosphide hybrid tandem solar cells were fabricated using surface-activated bonding. The bottom surface of nitride top cells grown on GaN substrates was bonded on the top surface of InGaP-based bottom cells grown on n-GaAs substrates. Their tandem-cell operation was successfully demonstrated by confirming that the open-circuit voltage (VOC) of tandem cells was enhanced. It was also found that the electrical properties of the bonding interface do not induce fatal effects on the performance of the tandem cells.

Surface-activated-bonding-based InGaP-on-Si double-junction cells

“…27) We successfully bonded the backsides of nitride-based cells fabricated on GaN substrates were successfully bonded to epitaxially grown InGaP cell structures by SAB so that nitride/InGaP-double-junction cells were formed. 28) We also measured the I-V characteristics of p-n junctions fabricated from a variety of semiconductor layers with different doping concentrations. 29) We found that the resistance across the bonding interface R interface decreased as the concentrations of impurities in p-and n-doped layers increased.…”

Multijunction GaInN-based solar cells using a tunnel junction

“…A multijunction GaInN-based solar cell was previously fabricated by the mechanical stack method. 22) On the other hand, there is no report of a multijunction nitride-based solar cell using a tunnel junction fabricated by crystal growth.…”