Performance Improvement of a Nonvolatile UV TD Sensor Using SAHAOS with a High Temperature Annealed, Partially Nano-Crystallized Trapping Layer

Abstract

This study shows that a silicon–aluminum oxide–hafnium aluminum oxide-silicon oxide–silicon capacitor device with a high temperature pre-metal-anneal-treated and partially-nanocrystallized hafnium aluminum oxide, (hereafter PNC-SAHAOS) can successfully increase the performance of a nonvolatile ultraviolet radiation total dose (hereafter UV TD) sensor. The experimental results show that the UV-induced threshold voltage VT shift of PNC-SAHAOS was 10 V after UV TD 100 mW·s/cm2 irradiation. The UV-induced charge density of PNC-SAHAOS is almost eight times that of amorphous silicon–aluminum oxide–silicon nitride–silicon dioxide–silicon SANOS. Moreover, the charge fading rate of ten-years retention on PNC-SAHAOS, even at 85 °C, is below 10%. At 85 °C, the charge fading rate of ten-years retention on amorphous SANOS is almost twice that on PNC-SAHAOS. These results strongly suggest that PNC-SAHAOS could be the most promising candidate for next-generation nonvolatile UV TD sensor technology.

Improve the Performance of SONOS Type UV TD Sensors Using IOHAOS with Enhanced UV Transparency ITO Gate

“…This positive V T shift result is the same as former research [11,12]. However, in former studies, the V T shift of poly silicon-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon SAHAOS with the poly silicon gate device is only 10 V under 405U100G25 [18][19][20]. Therefore, the V T shift of IOHAOS-I2H2 was almost 1.25 times that of poly silicon-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon SAHAOS with the poly silicon gate device.…”

“…As illustrated in Figure 6b, The IOHAOS-I2H2 shows larger UV generated V T shift than the IOHAOS-I2H1 and IOHAOS-I2H3 devices. As illustrated in the former study, it is noted that UV generated charges can be trapped not only in HfAlO nanocrystals, but also in amorphous regions of the HfAlO trapping layer [18][19][20]. Therefore, it is known that the partially nanocrystallized HfAlO trapping layer has a higher trap density than the complete whole amorphous HfAlO trapping layer and whole poly crystalline structure like HfAlO.…”

“…For IOHAOS-I2H2 under 405 nm UV irradiation, the sensitivity was about 10 KV•cm 2 /J, the resolution was about 10 nJ/cm 2 , the sensing range was about 10 nJ/cm 2 to 1 J/cm 2 , and the fading rate was about 10% for 10 years retention in this study. However, for SAHAOS under 405 nm UV irradiation, the sensitivity was about 3 KV•cm 2 /J, the resolution was about 100 nJ/cm 2 , the sensing range was about 100 nJ/cm 2 to 1 J/cm 2 , and the fading rate was about 10% for 10 years retention [18][19][20]. It is noted that the resolution and sensitivity of IOHAOS-I2H2 UV TD sensor were much better than those of SAHAOS with the poly gate.…”

“…Therefore, it is known that the partially nanocrystallized HfAlO trapping layer has a higher trap density than the complete whole amorphous HfAlO trapping layer and whole poly crystalline structure like HfAlO. Therefore, it can be concluded that the partially nanocrystallized HfAlO trapping layer with 1000 • C 30 s PDA has a larger trap density than the whole amorphous HfAlO with 900 • C 30 s PDA and whole poly crystalline structure like HfAlO with 1100 • C 30 s PDA [18][19][20].…”

“…In next generation, a silicon-silicon dioxide-hafnium oxide-silicon dioxide-silicon (SOHOS) like device with high-k gate dielectric materials have better performance of NVM than silicon-silicon oxide−silicon nitride-silicon oxide-silicon SONOS due to their scalability [13][14][15][16][17]. In former studies, a poly silicon-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon SAHAOS with poly silicon gate device has shown the better performance as NVM UV TD sensor than a silicon-silicon oxide-silicon nitride-silicon oxide-silicon SONOS sensor [18][19][20].…”