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Fig. 1. Three-dimensional geometrical model of the two-color LWIR- VLWIR detector used in the numerical simulations. The calculated quantum efficiency (QE) for this device structure is presented in Fig. 2. As can be seen, the detector QE in the VLWIR spectral range is limited to a value of 45% for a VLWIR contact of 25-um square. This is due to the large portion of the VLWIR diode that is short-circuited by the common contact. As can be seen in Fig. 1, the common con-

Figure 1 Three-dimensional geometrical model of the two-color LWIR- VLWIR detector used in the numerical simulations. The calculated quantum efficiency (QE) for this device structure is presented in Fig. 2. As can be seen, the detector QE in the VLWIR spectral range is limited to a value of 45% for a VLWIR contact of 25-um square. This is due to the large portion of the VLWIR diode that is short-circuited by the common contact. As can be seen in Fig. 1, the common con-

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Fig. 2. Calculated QE for the multicolor (LWIR/VLWIR) device struc- ture shown in Fig. 1, for different geometries of the VLWIR contacts.
Fig. 2. Calculated QE for the multicolor (LWIR/VLWIR) device struc- ture shown in Fig. 1, for different geometries of the VLWIR contacts.
SIN SOE a Re ST es SE SRR ee Danes im eee ge ee em ere ~ As the spot is moved in the pixel area, the photo- current is computed for each position. The result obtained for a wavelength of 22 4m is presented in Figs. 3 and 4, respectively, for a 5-um and 25-um square VLWIR contacts. It can be noticed that in the Fig. 3. Calculated normalized photo-response when the pixel area is scanned with a 5-um square laser spot and 22-um wavelength (VLWIR contact 5-um square).
SIN SOE a Re ST es SE SRR ee Danes im eee ge ee em ere ~ As the spot is moved in the pixel area, the photo- current is computed for each position. The result obtained for a wavelength of 22 4m is presented in Figs. 3 and 4, respectively, for a 5-um and 25-um square VLWIR contacts. It can be noticed that in the Fig. 3. Calculated normalized photo-response when the pixel area is scanned with a 5-um square laser spot and 22-um wavelength (VLWIR contact 5-um square).
The simulation of a single 3-D pixel structure is the first step to understand the electrical interac- tion between pixels in a focal plane array (FPA). Furthermore, in the case of a FPA, the effect of other regions, for example, etched sections, of the devices that are not involved in the detection process needs to be investigated. In this case, the so-called fill factor has to be evaluated and if possible maximized without compromising the FPA performance. To this end, we have performed a set of simulations of multipixel structures that include four or more pixels. The same simulation model used before is applied to a section of an FPA to investigate the pixel-to-pixel interaction. Figure 5 presents an ex- Fig. 5. An example of a multicolor LWIR/VLWIR FPA nine-pixel sec- tion used in the simulation. Pixels 4, 5, and 6 have been removed from the plot to show the photo-generated carrier distribution at wavelength of 12 um in the center pixel.
The simulation of a single 3-D pixel structure is the first step to understand the electrical interac- tion between pixels in a focal plane array (FPA). Furthermore, in the case of a FPA, the effect of other regions, for example, etched sections, of the devices that are not involved in the detection process needs to be investigated. In this case, the so-called fill factor has to be evaluated and if possible maximized without compromising the FPA performance. To this end, we have performed a set of simulations of multipixel structures that include four or more pixels. The same simulation model used before is applied to a section of an FPA to investigate the pixel-to-pixel interaction. Figure 5 presents an ex- Fig. 5. An example of a multicolor LWIR/VLWIR FPA nine-pixel sec- tion used in the simulation. Pixels 4, 5, and 6 have been removed from the plot to show the photo-generated carrier distribution at wavelength of 12 um in the center pixel.
Fig. 4. Calculated normalized photo-response when the pixel area is scanned with a 5-um square laser spot and 22-um wavelength (VLWIR contact 25-um square).
Fig. 4. Calculated normalized photo-response when the pixel area is scanned with a 5-um square laser spot and 22-um wavelength (VLWIR contact 25-um square).
Fig. 6. An example of cross-talk calculation for the nine-pixel FPA. The plot shows the minority carrier (holes) distribution in the entire structure when only the center pixel is illuminated. Pixels 2, 3, 4, 5, 6, 7, 8, and 9 have been removed from the plot to show the minority carrier current. The results presented here show that robust mod- eling and simulation is clearly needed for multicolor
Fig. 6. An example of cross-talk calculation for the nine-pixel FPA. The plot shows the minority carrier (holes) distribution in the entire structure when only the center pixel is illuminated. Pixels 2, 3, 4, 5, 6, 7, 8, and 9 have been removed from the plot to show the minority carrier current. The results presented here show that robust mod- eling and simulation is clearly needed for multicolor
Related topics:
Electronic MaterialsSimulation experimentElectrical and Electronic EngineeringIR DetectorFocal Plane Array
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