Hello,
I have a question regarding the paper, "Microbolometer Technology Using Serial PN-Diodes" published in IEEE. The paper was presented at the 2013 ISCDG IEEE International Semiconductor Conference in Dresden.
In the paper the authors use 4 pn diodes connected in series as a temperature sensor. This offers an advantage over a single pn diode as the voltage temperature coefficient is increased (-7mV/K for 4 diodes as opposed to -1.7mV/K for 1). In effect the sensitivity is increased by 4.
They state and indeed show graphs as evidence that the 4 diodes have to be "electrically isolated" by etching the silicon between them. However the diodes are in effect not electrically isolated as they are connected together using metal interconnects.
I contacted the authors for more details however they were unable to assist as they are bound by intellectual property agreements with collaborators.
Any ideas?
Thanks
Interesting question. I wasn't able to download the paper you mentioned but I think the idea is probably somewhat similar to the 2001 paper I attached. Looking at figure 8 b, I think that it may provide a clue.
If you dope a series of p and n areas next two each other pnpnpnpthen you would get a bunch of pn interfaces that would point . if you fabricate mpnmpnmpnmpm and the metal contacts are ohmic then you would get a set of diodes that would all point in the same direction m
Hi John,
Thanks for your response. I attach the paper I mention in my original post.
In the 2001 paper, according to figure 10b the silicon is etched only between the pixels and not the individual diodes. This is in contrast to Fig. 1 of the attached paper where not only is the silicon etched between pixels, but also the diodes.
Pretty sure in Figure 10B they etched down to the oxide layer between the diodes, then did a metal deposition to connect them. Then the diodes are electrically isolated and the metal connects them in series. In Figure 10A the hole pixel is thermally isolated by etching, and it is hard to see the detail on the diodes, but the idea I think that if the pixel is isolated then the whole platfrorm of burried oxide and the 4 diodes isolated and in series is suspended and heats up with incident light. In the new paper it is a little harder to trace out but I think it is probably the same principle.
Thanks John - I concur with your assessment. (sorry for the late reply).
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