Sb-heterostructure backward diode detectors with ultrathin tunnel barriers

Sb-heterostructure backward diodes have proven to be a strong contender for millimeter-wave direct detection applications, primarily due to their high sensitivity, low noise and high frequency response. It has been shown that thinning the AlSb barrier thickness (from 32 A to 11 A) greatly reduced the junction resistance (Rj) and thus the associated Johnson noise. However this lowered the curvature coefficient. A further refinement to the heterostructure design uses Be ¿-doping in the cathode layer to improve the band alignment, which resulted in reduced noise equivalent power (NEP) and improved sensitivity. In this work, we present a study of the effects of scaling the barrier thickness to as thin as 7 A, and the improvements made by cathode ¿-doping based on the 7 A AlSb tunnel barrier structure.