Type-II superlattice photodetectors versus HgCdTe photodiodes

Since the first paper published by Sakaki and Esaki in 1978, it is well known that InAs and GaSb constitute a nearly lattice-matched material system offering great flexibility in the design of IR optoelectronic devices. After four decades, the III-V type-II superlattice (T2SL) detector technology is under strong development as a possible alternative to HgCdTe. The novel ideas coming in design of detectors have enhanced the position of T2SLs in IR materials detector technology. It appears that T2SLs are especially helpful in the design of unipolar barriers. In this paper fundamental physical properties of two material systems, HgCdTe and T2SLs, are compared together with their influence on detector performance: dark current density, RA product, quantum efficiency, and noise equivalent different temperature. In comparison with HgCdTe, fundamental properties of T2SLs are inferior. On the other hand, T2SL and barrier detectors have several advantages to include lower tunnelling and surface leakage currents, and suppressed Auger recombination mechanism. Up to date, the promise of superior performance of these detectors has not been realized yet. In the paper we present that the performance of T2SL detectors (dark current, current responsivity, and noise equivalent difference temperature) is lower than bulk HgCdTe photodiodes. Due to stronger, less ionic chemical bonding of III-V semiconductors, these materials are attractive due to manufacturability and stability. It is also predicted that the interband T2SL quantum cascade devices will outperform the performance of the high operating temperature HgCdTe detectors.