Passivation of type-II InAs∕GaSb double heterostructure

Abstract

Focal plane array fabrication requires a well passivated material that is resistant to aggressive processes. The authors report on the ability of type-II InAs∕GaSb superlattice heterodiodes to be more resilient than homojunctions diodes in improving sidewall resistivity through the use of various passivation techniques. The heterostructure consisting of two wide band gap (5μm) superlattice contacts and a low band gap active region (11μm) exhibits an R0A averaging of 13Ωcm2. The devices passivated with SiO2, Na2S and SiO2 or polyimide did not degrade compared to the unpassivated sample and the resistivity of the sidewalls increased to 47kΩcm.

New material systems for third generation infrared photodetectors

“…In general, the inversion potentials are bigger for higher band gap materials, and therefore SiO 2 can passivate high band gap materials (MWIR photodiodes) but not low band gap material (LWIR photodiodes). Using this property, a double heterostructure that prevents the inversion of the high band gap p-type and n-type superlattice contact regions has been proposed [62]. For such structure, the surface leakage channel at the interface between the active region and the p-or n-contacts is considerably decreased (see Fig.…”

“…9). For this structure, an effective passivation is low-temperature, ion-sputtered SiO 2 passivation [62]. Passivation with polyimide has also proved very effective [63].…”

Infrared Detectors for the Future

“…Using this property, a double heterostructure that prevents the inversion of the high band gap p-type and n-type superlattice contact regions has been proposed with low--temperature ion-sputtered SiO 2 passivation [47]. Passivation with polyimide has also proved very effective [48].…”

Investigation of the lower temperature SiO2 surface passivation technology on InAs/GaSb superlattice detectors

“…Several surface passivation attempts have been proposed to minimize the dark currents, thereinto, SiO 2 passivation, which can be compatible with standard semiconductor fabrication procedures, is still the dominant and most suitable passivation technique for T2SL application. However, SiO 2 film deposition usually utilizes a plasma enhanced chemical vapor deposition process conducted at high temperatures and exposure of SLs materials to high temperatures could degrade the overall device performance [6]. So special care needs to be taken to develop a low-temperature process of SiO 2 deposition technology to prevent SLs period intermixing and improve the electrical performance.…”

“…Among these current mechanisms, the minimal of surface leakage is crucial to be resolved for reducing the total dark current and obtaining the high resolution imaging system. Generally, surface leakage is believed to originate from the abrupt termination of the periodic crystalline structure, contamination from processing, and fixed charges within the passivation layer, which can generate band bending on mesa-sidewalls, this band bending causes electron accumulation or type inversion at sidewall surfaces, resulting in a conduction channel along sidewalls [6,7]. Several surface passivation attempts have been proposed to minimize the dark currents, thereinto, SiO 2 passivation, which can be compatible with standard semiconductor fabrication procedures, is still the dominant and most suitable passivation technique for T2SL application.…”