Figures

Figure 1

Spectral detectivities for selected photodetectors.

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Figure 2

GaN/AlGaN photodiode structure. At the right, optical absorption spectra obtained for the AlGaN and GaN layers of the device are shown to illustrate the UV responsivity band.

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Figure 3

Hybridization process for UV digital camera.

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Figure 4

Nomarski photographs of a 32 x 32 GaN/AlGaN photodiode array.

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Figure 5

Nomarski photographs of a 32 x 32 silicon ROIC.

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Figure 6

Hybridized GaN/AlGaN UV photodiode array mounted on PC board prior to testing .

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Figure 7

Experimental setup used at NVL to evaluate the visible-blind UV digital camera.

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Figure 8

Back-lighted UV alpha-numeric ("NCSU") source used for nitride FPA testing at NVL.

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Figure 9

Spectral responsivity of discrete (200 µm x 200 µm) GaN/AlGaN heterostructure photodiode operating in the photovoltaic mode (zero bias).

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Figure 10

Current-voltage characteristics of a discrete GaN/AlGaN p-i-n heterostructure photodiode (left). The dynamic resistance versus voltage is also shown (right). Note that the diode dynamic resistance peaks near zero-bias and is very large. This implies high optical detectivity. R₀A = 1.5 x 10⁹ -cm² and D* = 6.1 x 10¹³ cm Hz^1/2W^-1 were obtained for this device.

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Figure 11

First demonstration of a visible-blind UV image from a III-V nitride-based photodiode array. The image from the FPA was recorded at NVL on July 28, 1999.

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Figure 12

Comparison of UV source (left) with digital image generated by the GaN/AlGaN focal plane array of visible-blind UV sensitive photodiodes (right).

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