Few-Layer Black Phosphorus Field-Effect Transistors with Reduced Current Fluctuation

Abstract

We investigated the reduction of current fluctuations in few-layer black phosphorus (BP) field-effect transistors resulting from Al2O3 passivation. In order to verify the effect of Al2O3 passivation on device characteristics, measurements and analyses were conducted on thermally annealed devices before and after the passivation. More specifically, static and low-frequency noise analyses were used in monitoring the charge transport characteristics in the devices. The carrier number fluctuation (CNF) model, which is related to the charge trapping/detrapping process near the interface between the channel and gate dielectric, was employed to describe the current fluctuation phenomena. Noise reduction due to the Al2O3 passivation was expressed in terms of the reduced interface trap density values D(it) and N(it), extracted from the subthreshold slope (SS) and the CNF model, respectively. The deviations between the interface trap density values extracted using the SS value and CNF model are elucidated in terms of the role of the Schottky barrier between the few-layer BP and metal contact. Furthermore, the preservation of the Al2O3-passivated few-layer BP flakes in ambient air for two months was confirmed by identical Raman spectra.

Stabilizing ultra-thin black phosphorus with in-situ-grown 1 nm-Al2O3 barrier

“…Also, numerous attempts have focused on the passivation via a relatively thick (10 nm or above) Al 2 O 3 layer grown on top of the BP flakes by ALD. 12,[22][23][24][25][26][27][28][29][30][31] Some attempts to reduce the thickness of the capping A 2 O 3 have also been reported. 32 Thin capping may simultaneously passivate and serve as a tunnel barrier (which may even lead to improved electrical contacts 33,34 ) representing a double advantage over thick capping in which electrical contacts must be patterned before passivation (ex-situ).…”

Electrically Tunable Energy Bandgap in Dual-Gated Ultra-Thin Black Phosphorus Field Effect Transistors

“…Various efforts have been made to encapsulate BP devices to improve its environmental stability. Among them, atomic layer deposition (ALD) of Al2O3 is a widely chosen method due to its technical maturity and the high quality of the encapsulating layer [39][40][41] . However, it has been reported that the deposition of Al2O3 on BP may lead to the oxidation of BP 42 .…”

2D Black Phosphorus: from Preparation to Applications for Electrochemical Energy Storage

“…For the encapsulation method, encapsulation layers, such as oxidized aluminum (AlO x ),149, 156, 157, 158, 159 h‐BN,151, 160, 161 polymer,100, 162, 163, 164 SiO 2 ,150 MoS 2 ,165 graphene oxide (GO),166 and graphene,161, 167, 168 were widely applied as barriers to protect 2D BP from its structure and chemical degradation. AlO x layer was deposited on BP devices by using the atomic layer deposition (ALD) process, where it can block surface reactions with ambient air.…”