Ultrathin delta doped GaAs and AlAs tunnel junctions as interdevice ohmic contacts

Ultrathin (200 Å), highly conductive GaAs and AlAs p/n junction tunnel diodes were fabricated using delta doping. The current carrying capacity of these tunnel diodes is the highest reported to date. The GaAs tunnel junction is capable of handling over 30 A/cm2 at a voltage drop of only 0.02 V, and the AlAs tunnel diode is capable of handling 27 A/cm2 at 0.10 V. These tunnel junctions are useful for interconnecting three-dimensional integrated circuits, integrated optoelectronic devices, and monolithic multijunction solar cells. The delta doping of tunnel junctions to form interdevice ohmic contacts can also be applied to other material systems as well as any devices requiring vertical interconnection.