Improved determination of matrix compostion of Hg1−xCdxTe by SIMS

A model is proposed to explain disparities found in the operability values and histograms for long-wavelength infrared HgCdTe focal-plane arrays fabricated on Si substrates compared with those fabricated on CdZnTe. The starting point for the model is the close agreement between the aerial density of discrete species (particles, contamination spots, crystalline defects on Si surface) in various interfaces in the HgCdTe/CdTe/Si structure and the density of failed pixels in the array. The density of discrete species is acquired by applying a newly developed variation of the secondary-ion mass spectrometry (SIMS) depth-profiling technique to samples that have been deuterated to enhance detection. A mechanism of selective activation of threading dislocations in a HgCdTe layer on Si is proposed to link discrete species with failed detector pixels.

Section: Resultsmentioning

confidence: 99%

The Distribution Tail of LWIR HgCdTe-on-Si FPAs: a Hypothetical Physical Mechanism

Bubulac

Benson

Jacobs

et al. 2011

“…As with the previous CdCs + /TeCs + method, the As can be measured together with Cd composition, and a point-by-point sputtering rate correction can be made to the entire profile. 2 With an accurate Cd composition profile for the entire HgCdTe layer, more accurate depth correction can be obtained.…”

Section: Resultsmentioning

confidence: 99%

“…The lamented magnet has mass range of 500 amu, much greater than 280 amu on the IMS-4f instrument that we used in previous studies. 2,4 The samples are bombarded by a focused Cs+ primary ion beam with net impact energy of 5 keV and about 100 nA of beam current. The beam is rastered over a square area of 200 lm on a side.…”

Section: Methodsmentioning

confidence: 99%

Accurate Determination of the Matrix Composition Profile of Hg1–x Cd x Te by Secondary Ion Mass Spectrometry

Wang

Price

2007

Self Cite

In this report, we present a new secondary ion mass spectrometry (SIMS) analysis technique to provide accurate Cd composition profiles based on the measurement of HgCs + and CdCs + cluster ions. Study of Hg 1-x Cd x Te samples with different x values shows that x/(1 ) x) is linearly proportional to HgCs + / CdCs + over the range of x = 0.2 to x = 0.9. This technique allows us to obtain an accurate Cd profile for a multilayer HgCdTe sample with different x values for each layer using a single standard with known x value.

“…At large values of N D , most of the recombination occurs as Auger recombination, and the fractional radiative recombination goes to zero as 1/N D . The radiative-recombination fraction has a maximum at an intermediate value, given by (10) which follows by setting the derivative with respect to N D of Eq. 9 to zero and solving for N D,Max .…”

Section: Discussionmentioning

confidence: 99%

Spectral crosstalk by radiative recombination in sequential-mode, dual mid-wavelength infrared band HgCdTe detectors

Coussa

Gallagher

Kosai

et al. 2004

For small pixel, infrared (IR) focal plane arrays (FPAs), Raytheon Vision Systems' architecture for integrated, dual-band detectors uses the sequential mode of the n-p ϩ -n configuration. There is a single indium bump per pixel, leaving the p ϩ layer floating, and the operating polarity of the bias selects the spectral sensitivity by reverse-biasing the active p-n junction. Photogenerated minority carriers in the absorber layer of the forward-biased inactive photodiode are lost through recombination. This paper is the first report of a new optical crosstalk mechanism that occurs in sequential-mode, dual-band detectors. In the long-wavelength mode under out-of-band, short-wavelength illumination, radiative recombination yields emission near the bandgap energy of the shortwavelength absorber layer, resulting in a spurious short-wavelength response that appears as spectral crosstalk. We present experimental and device modeling results on the spectral crosstalk in molecular-beam-epitaxy-grown HgCdTe arrays with the cutoff wavelength of both bands in the 4-5-µm range.