The nipnip-THz-emitter: photomixing based on ballistic transport

Abstract

We report on a novel concept for THz-photomixers based on quasi-ballistic transport in an asymmetric nipnipdoping-superlattice. Due to tansport-optimized i-layers the emitted powers are not transit-time-limited up to 1 T Hz. Furthermore the capacitance and hence the RC-roll-off is minimized by increasing the number of pin-periods. The frequencydependence of the nipnip-emitter proofs to be superior to corresponding pin-photomixers.

THz-photomixer based on quasi-ballistic transport

“…In addition, the field dependence of the absorption coefficient at photon energies close to the band gap could be used to get information about the laserpower-dependent screening of the built-in field in the i-layer. The field screening deduced from these experiments was in good agreement with the behaviour expected from the studies of the dark current density versus voltage characteristics of the recombination diodes [11].…”

“…The high recombination current densities at 1 V, corresponding to recombination rates of about 5 × 10 21 or 5 × 10 23 cm −2 s −1 electron and hole recombinations in the LT-GaAs layer or the ErAs layer, respectively, are rather due to the large sheet carrier densities in the range of 10 12 to 10 13 cm −2 than to particularly short tunnelling capturing times (of the order of ns for LT-GaAs to several ps in the ErAs layers). Equally favourable results have recently been obtained in InGaAs-recombination diodes [11].…”