Fabrication and Characterization of GaAs Tunnel Diode and ErAs Nanoparticles Enhanced GaAs Tunnel Diode for Multijunction Solar Cell

Abstract

We report here the fabrication and characterization of GaAs tunnel diode (TD) and ErAs nanoparticles (Nps) enhanced GaAs TD. Four GaAs TDs with different contact area were fabricated by using MOCVD. We found extremely high peak current density of ∼250A/cm2 for the TD with r=0.25mm contact area. Moreover a hysteresis loop was appeared during sweeping up and sweeping down the external voltage. A ‘vector load line model’ was proposed to explain the origin of the shape of the hysteresis loop and the onset of the bistability occurred at the intersect of the loadline and the current-voltage (I-V) curve of TD. Meanwhile, we have grown ErAs Nps on GaAs(100) surface by using MBE and succeeded in overgrowth of GaAs after ErAs deposition. GaAs(p+)/ErAs(Nps)/GaAs(n+) TDs were fabricated and characterized. We found the GaAs sample containing 70s deposition of ErAs showed the best TD behavior. No TD behavior was observed for the sample without addition of ErAs Nps, clearly indicating the strong tunneling enhancement effect from ErAs Nps.

Improved performance of GaAs tunnel diode by embedding InAs quantum dot layer for tandem solar cells

“…7,8) Recently, Sogabe et al have shown the performance enhancement of GaAs TDs embedded with ErAs nanoparticles. 23) However, ErAs has a rock-salt crystal structure that is different from the zinc-blende structure, which is the crystal structure of the other compositing layers used in making tandem solar cells. This difference in crystal structure can result in the degradation of material quality owing to the formation of anti-phase domain (APD) defects, 9) and ErAs is known to easily oxidize in atmosphere.…”