Low Dark Current Small Pixel Large Format InGaAs 2D835309

Low Dark Current Small Pixel Large Format InGaAs 2D Photodetector Array Development at Teledyne Judson Technologies Henry Yuan, Mike Meixell, Jiawen Zhang, Philip Bey, Joe Kimchi, Louis C. Kilmer

Teledyne Judson Technologies

221 Commerce Drive, Montgomeryville, PA 18936

ABSTRACT

Teledyne Judson Technologies (TJT) has been developing technology for small pixel, large format, low dark current, and low capacitance NIR/SWIR InGaAs detector arrays, aiming to produce <10µm pixels and >2Kx2K format arrays that can be operated at or near room temperature. Furthermore, TJT is now developing technology for sub-10µm pixel arrays in response to requirements for a variety of low light level (LLL) imaging applications. In this paper, we will review test data that demonstrates lower dark current density for 10-20µm pixel arrays. We will present preliminary results on the successful fabrication of test arrays with pixels as small as 5µm. In addition, a lot of effort has been made to control and reduce the detector pixel capacitance which can become another source of detector noise. TJT is also developing 4” InGaAs wafer process and now offers four different types of InGaAs 2D arrays/FPAs that are tailored to different customer requirements for dark current, capacitance, spectral response, and bias range.

Keywords: InGaAs, photodetector, 2D array, dark current, small pixel, capacitance, infrared focal plane array,

4” wafer, substrate removal

1.INTRODUCTION

There is an increasing interest in large format (>1Kx1K) and small pixel (<20µm) InGaAs focal plane arrays (FPAs) for a variety of low light level (LLL) imaging applications such as night vision. These applications demand extremely low detector dark current and Si read-out integration circuit (ROIC) noise1. For near infrared (NIR) and short wavelength infrared (SWIR) imaging, InGaAs is the widely preferred detector material due to its low dark current, mature fabrication technology, excellent uniformity, low production cost, and operation at or near room temperature using thermoelectric cooling. The detector array is formed in MOCVD-grown In0.53Ga0.47As, lattice matched to an InP substrate. The spectral response typically covers 0.9-1.7µm at room temperature, and can be extended further to the visible wavelength range by removing the InP substrate. In recent years, there has been intensive effort in developing advanced InGaAs array technology for LLL SWIR imaging1-7, and remarkable improvements of detector dark current and ROIC noise have been accomplished. However, there remains tremendous challenge in meeting the demands for lower noise, smaller pixel, larger format, higher operating temperature, and lower production cost.Funded by IR&D, Teledyne Judson Technologies (TJT) has developed technology for InGaAs FPAs, including the most advanced technology for InGaAs 2D arrays. We developed a unique process that is highly suitable for very small pixel (<10-15µm) and large format (>1Kx1K) arrays. In addition, this novel process offers a number of other potential advantages, such as very low dark current, low production cost, and high uniformity and operability. This paper reviews our progress in detector array development, including (1) developing 4” wafer technology and several types of detector arrays, (2) reducing dark current density for 10-20µm pixel arrays, (3) developing sub-10µm pixel array technology and demonstrating the feasibility of making 5µm pixel arrays, and (4) reducing the capacitance of small pixels.

Infrared Technology and Applications XXXVIII, edited by Bjørn F. Andresen, Gabor F. Fulop, Paul R. Norton,

Proc. of SPIE Vol. 8353, 835309 · © 2012 SPIE · CCC code: 0277-786X/12/$18 · doi: 10.1117/12.921232

Proc. of SPIE Vol. 8353 835309-1

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