Modulation of the n-channel conductivity in liquid phase epitaxially grown p-n-p doped GaAs submicron structures

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Abstract
p‐n‐p doped GaAs structures with active n‐doped layers with thicknesses of 250 nm>dn>15 nm and doping concentrations of 3×1018 cm−3>n≥1×1017 cm−3, and 6×1017 cm−3>p>7×1015 cm−3, have been grown by liquid phase epitaxy. The modulation of the n‐channel conductivity σnn(Unp) by an external potential Unp between the p and n‐layers has been measured at 77 and 300 K. The characteristic curves σnn(Unp) are interpreted by the modulation of the two‐dimensional carrier concentration n(2) (Unp) with Unp and by the variation of the mobility μn(defn) on the effective channel thickness defn(Unp) . The sensitivity of the p‐n‐p structure to small variations in design parameters is shown for the threshold voltage Uthnp . In p‐n‐p specimens with n∼1×1017 cm−3, p16 cm−3 and dn≂40 nm, an unexpected enhancement of the conductivity up to one order of magnitude between 300 and 77 K is observed. This is explained essentially by a hole freeze out due to the high acceptor level of the Ge dopant in the p layers and simultaneous release of electrons in the n channel.