Tunable bandgap energy of fluorinated nanocrystals for flash memory applications produced by low-damage plasma treatment

Abstract

A plasma system with a complementary filter to shield samples from damage during tetrafluoromethane (CF(4)) plasma treatment was proposed in order to incorporate fluorine atoms into gadolinium oxide nanocrystals (Gd(2)O(3)-NCs) for flash memory applications. X-ray photoelectron spectroscopy confirmed that fluorine atoms were successfully introduced into the Gd(2)O(3)-NCs despite the use of a filter in the plasma-enhanced chemical vapour deposition system to shield against several potentially damaging species. The number of incorporated fluorine atoms can be controlled by varying the treatment time. The optimized memory window of the resulting flash memory devices was twice that of devices treated by a filterless system because more fluorine atoms were incorporated into the Gd(2)O(3)-NCs film with very little damage. This enlarged the bandgap energy from 5.48 to 6.83 eV, as observed by ultraviolet absorption measurements. This bandgap expansion can provide a large built-in electric field that allows more charges to be stored in the Gd(2)O(3)-NCs. The maximum improvement in the retention characteristic was >60%. Because plasma damage during treatment is minimal, maximum fluorination can be achieved. The concept of simply adding a filter to a plasma system to prevent plasma damage exhibits great promise for functionalization or modification of nanomaterials for advanced nanoelectronics while introducing minimal defects.

Flexible Transparent Electrode of Hybrid Ag-Nanowire/Reduced-Graphene-Oxide Thin Film on PET Substrate Prepared Using H2/Ar Low-Damage Plasma

“…The slits on the upper plate are aligned with the stripes on the lower plate, which can block high-energy collimated ions and prevent direct exposure of the samples to UV radiation. In our previous study [27,28], we confirmed that the UV intensity can be reduced by more than 95%. Therefore, the filter can efficiently shield the samples from plasma damage caused by energetic ions and UV radiation.…”

“…In our previous studies, we developed a low-damage plasma treatment (LDPT) method for the functionalization of nanocrystalline and thin-film materials for applications in flash memory devices and ion sensors, respectively [27,28]. Both results demonstrated successful functionalization with minimal plasma damage.…”

Data Retention Characterization of Gate-Injected Gold-Nanoparticle Non-Volatile Memory with Low-Damage CF4-Plasma-Treated Blocking Oxide Layer

“…After the Au-NPs had formed, a 20-nm-thick SiO 2 layer was deposited via plasma-enhanced chemical vapor deposition (PECVD) as the BO layer, where the samples were kept in a SiH 4 and N 2 O ambient at a radio frequency (RF) power of 50 W with gas flow rates of 5 and 200 sccm, respectively. Thereafter, a low-damage CF 4 plasma treatment was performed in a PECVD system with a quartz filter, filtering high-energy electrons, ions, and ultra-violet (UV) radiation to reduce plasma damage on the BO layer [ 15 ]. The chamber was first evacuated to 10 −6 Torr and gradually heated to 300 °C.…”