Picosecond photoconductivity using a graded bandgap Al/sub x/Ga/sub 1-x/As active detecting layer

Improved responsivity for picosecond photoconductors is achieved by utilizing a graded bandgap Al/sub x/Ga/sub 1-x/As active detecting layer grown on a high-defect-density, low-temperature GaAs layer by MBE (molecular beam epitaxy). By taking advantage of the superior transport properties of the graded Al/sub x/Ga/sub 1-x/As layer, order-of-magnitude improvement in responsivity has been demonstrated, along with 2-6 times improvement in peak photocurrent response. This provides a capability to design photodetector speeds into the <10-ps regime.<
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