Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission

• Published in: Applied physics letters 2014-01, Vol.104 (1), p.13112
• Main Authors: El-Atab, Nazek, Ozcan, Ayse, Alkis, Sabri, Okyay, Ali K., Nayfeh, Ammar
• Format: Article
• Language: English
• Subjects: Applied physics; Dependence; Electric fields; ELECTRIC POTENTIAL; EMISSION; HOLES; Nanoparticles; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; PARTICLES; PHONONS; Programming; SILICON; Spin coating; SPIN-ON COATING; Threshold voltage; TRAPPING; TUNNEL EFFECT; Zinc oxide; ZINC OXIDES
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4861590

A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2 nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (ΔVt) vs. programming voltage is studied with and without the silicon nanoparticles. Applying −1 V for 5 s at the gate of the memory with nanoparticles results in a ΔVt of 3.4 V, and the memory window can be up to 8 V with an excellent retention characteristic (>10 yr). Without nanoparticles, at −1 V programming voltage, the ΔVt is negligible. In order to get ΔVt of 3.4 V without nanoparticles, programming voltage in excess of 10 V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1 V the electric field across the 3.6 nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ΔVt vs. electric field across the tunnel oxide shows square root dependence at low fields (E  2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.