The AlGaN/GaN quantum-well heterostructures typically exhibit a positive
photoconductivity (PPC) during the light illumination. Surprisingly, we found
that introducing the GaN/AlN superlattice (SL) back barrier into N-polar
AlGaN/GaN quantum-well heterostructures induces a transition in these
heterostructures from PPC to negativie photoconductivity (NPC) as the SL period
number increased at room temperature. This transition occurred under an
infrared light illumination and can be well explained in terms of the
excitation of hot electrons from the two-dimensional electron gas and
subsequent trapping them in a SL structure. The NPC effect observed in N-polar
AlGaN/GaN heterostructures with SL back barrier exhibits photoconductivity
yield exceeding 85 % and thus is the largest ones reported so far for
semiconductors. Inoltre, NPC signal remains relatively stable at high
temperatures up to 400 K. The obtained results can be interesting for the
development of NPC related devices such as photoelectric logic gates,
photoelectronic memory and infrared photodetectors.

Questo articolo esplora i giri e le loro implicazioni.

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