Coupling Ferroelectric to colloidal Nanocrystals as a Generic Strategy to Engineer the Carrier Density Landscape
Résumé
The design of infrared nanocrystals-based (NCs) photodiodes faces a major challenge related to the identification of barriers with a well-suited band alignment or strategy to finely control the carrier density. Here, we explore a general complementary approach where the carrier density control is achieved by coupling a NC layer to a ferroelectric material. The up and down change in ferroelectric polarization directly impacts the NC electronic structure resulting in the formation of a lateral pn junction. This effect was uncovered directly using nano X-ray photoemission spectroscopy which shows a relative energy shift of 115 meV of the NC photoemission signal over the two different up-and down polarized ferroelectric regions, a shift as large as the open circuit value obtained in the diode stack. The performance of this pn junction reveals an enhanced responsivity and reduced noise that leads to a factor 40 increase in the detectivity value.
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