Bi-color and dual-band HgCdTe infrared focal plane arrays at Defir

Abstract

The purpose of this paper is to present the latest developments in Defir (LETI / Sofradir joint laboratory) in the field of bi-color and dual band infrared focal plane arrays (FPA) made with HgCdTe. The npn structure is achieved using the Molecular Beam Epitaxy (MBE) technique, planar ion implantation, and both dry and wet etching steps. This back to back diode architecture that allows a perfect spatial coherence with a high field factor and large quantum efficiencies needs only one indium bump connection per pixel. This makes it possible to achieve small pitches (below 25µm) and opens the way to the fabrication of large FPAs (TV/4 to TV) with reasonable wafer sizes. In this paper we present electro optical characterizations of 256x256 prototypes fabricated in Defir operating in two MWIR bands (3.1 and 5µm) with a pitch of 25µm that exhibit background limited performances together with a very high operability (above 99.9%) and NEDT below 22mK for integration time of only 0.5ms. In parallel an industrial product soon available from Sofradir has been developed with a 320x256 format and with a 30µm pitch operating in the same bands. This product exhibits the same operability and NETD as low as 15mK for an integration time as short as 1 ms. Finally, last results regarding 256x256 prototypes operating in MWIR/LWIR bands are presented, together with preliminary APD operating mode for the MWIR photodiodes of this last dual band detector.

Third-generation infrared photodetector arrays

“…Both HgCdTe photodiodes 31,[34][35][36][37][38] and QWIPs 2,28,32,39-44 offer multicolor capability in the SWIR, MWIR, and LWIR ranges. The performance figures of merit of state-of-the-art QWIP and HgCdTe FPAs are similar because the main limitations are related to the readout circuits.…”

128×128 dual-color ROIC with electrical crosstalk resistant design

“…With the continues development of infrared detectors, infrared systems have been applied in many various fields including military affairs, safety, process monitoring, environmental management, space sciences and so on [1] . In recent years, the realization of two-color infrared (IR) detection system has been the core of intense research and technological development.…”

Material considerations for third generation infrared photon detectors

“…Both HgCdTe photodiodes [5][6][7][8][9] and quantum well infrared photodetectors (QWIPs) [7,[10][11][12][13] offer the multicolour capability in the MWIR and LWIR range. The performance figures of merit of state-of-the-art QWIP and HgCdTe FPAs are similar because the main limitations come from the readout circuits.…”