Sb-heterostructure backward diode detectors with ultrathin tunnel barriers

Abstract

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 Å to 11 Å) greatly reduced the junction resistance (Rj) and thus the associated Johnson noise [1]. However this lowered the curvature coefficient. A further refinement to the heterostructure design uses Be δ-doping in the cathode layer to improve the band alignment, which resulted in reduced noise equivalent power (NEP) and improved sensitivity [2]. In this work, we present a study of the effects of scaling the barrier thickness to as thin as 7 Å, and the improvements made by cathode δ-doping based on the 7 Å AlSb tunnel barrier structure. © 2009 IEEE.