Narrow-gap InAs for heterostructure tunnelling

Recent experiments show that narrow-gap semiconductors have significant advantages for potential device applications of electron tunnelling. As a result of the small electron effective mass in InAs, the authors can observe resonant tunnelling through a 24 nm quantum well, the longest coherence distance reported for double-barrier heterostructures. Another novel finding is that single-barrier tunnelling devices of InAs/AlGaSb/InAs exhibit negative differential conductance at room temperature owing to the favourable band alignment. The high electron mobility in InAs will lead to lower parasitic device resistances and improved high-frequency performance compared to devices based on GaAs. To compare the experimental results with theory, the two-band model of a narrow-gap semiconductor has been incorporated in the standard calculation of tunnelling current-voltage characteristics.