Zinc diffusion in III-V semiconductors using a cubic-zirconia protection layer

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Abstract
Zinc was diffused into GaAs, Al0.38Ga0.62As, and GaAs0.6P0.4 using a 2000–3000-Å-thick yttria-stabilized cubic-zirconia (YSZ) protection layer to produce planar p-n junctions. The YSZ layer greatly reduced thermal decomposition of the semiconductor while allowing zinc to diffuse into the III-V semiconductors. The diffusion depth showed a square-root-of-time dependence for all samples protected with YSZ. Characterization of the GaAs diffused with the YSZ protection process indicates that the YSZ layer has virtually no effect on either the carrier concentration profile or activation energy. No thermal decomposition was observed by visual inspection following a diffusion using only elemental Zn on the GaAs, Al0.38Ga0.62As, or GaAs0.6P0.4 samples protected with a YSZ layer. Photoluminescence analysis shows that the YSZ-protected GaAs samples have higher luminescence efficiency relative to unprotected samples. Device fabrication has been demonstrated by combining the YSZ passivation process with selective area diffusion. Our results indicate that the YSZ diffusion procedure has greater tolerance to process variations than previously reported diffusion procedures for zinc in III-V semiconductors.