Influence of Pixel Etching on Electrical and Electro-Optical Performances of a Ga-Free InAs/InAsSb T2SL Barrier Photodetector for Mid-Wave Infrared Imaging

Maxime Bouschet,Rodolphe Alchaar,Francisco De Anda-Salazar,Clara Bataillon,Philippe Christol,Vignesh Arounassalame,Isabelle Ribet-Mohamed,Jean-Philippe Perez,Ulises Zavala-Moran,Nicolas Péré-Laperne

doi:10.3390/photonics8060194

Abstract

In this paper, the influence of etching depth on the dark current and photo-response of a mid-wave infrared Ga-free T2SL XBn pixel detector is investigated. Two wet chemical etching depths have been considered for the fabrication of a non-passivated individual pixel detector having a cut-off wavelength of 5 µm at 150 K. This study shows the strong influence of the lateral diffusion length of a shallow-etched pixel on the electro-optical properties of the device. The lowest dark current density was recorded for the deep-etched detector, on the order of 1 × 10−5 A/cm2 at 150 K and a bias operation equal to −400 mV. The corresponding quantum efficiency was measured at 60% (without anti-reflection coating) for a 3 µm thick absorbing layer. A comparison of experimental results obtained on the two kinds of etched pixels demonstrates the need for a deep-etching process combined with efficient passivation for FPA manufacturing.

Highlights

In the past ten years, barrier structure has become the standard design of antimonide-based (Sb-based) high-performance cooled infrared (IR) photodetectors, for Ga-free InAsSb bulk and InAs/InAsSb type-II superlattice (T2SL) devices operating in the mid-wave infrared (MWIR, 3–5 μm) spectral domain [1,2,3,4,5,6,7,8,9,10,11]
A barrier layer (BL) made of a large band gap material is inserted between the contact layer (CL) and the n-type absorbing layer (AL) to block the electron majority carriers without impeding the transport of the hole minority carriers
The objective of this paper is to study the influence of the etching depth of a nonpassivated pixel on electrical and electro-optical performances of an MWIR Ga-free InAs/

Summary

Introduction

The XBn barrier structure, if well designed and correctly fabricated, permits to control the dark currents in IR photodetectors. In this structure, a barrier layer (BL) made of a large band gap material is inserted between the contact layer (CL) and the n-type absorbing layer (AL) to block the electron majority carriers without impeding the transport of the hole minority carriers. A barrier layer (BL) made of a large band gap material is inserted between the contact layer (CL) and the n-type absorbing layer (AL) to block the electron majority carriers without impeding the transport of the hole minority carriers This device is called an unipolar barrier detector.

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