Black phosphorus (BP), a fast emerging 2D material, has shown great potential in future electronics and optoelectronics owing to its outstanding properties including sizable band gap and ambipolar transport characteristics. However, its hole conduction dominance, featured by a much larger hole mobility and the corresponding on-current than that of the electrons, renders the reliable modulation of its carrier type and density a key challenge, thereby hindering its application to complementary electronics. Here, we demonstrate an efficient and reliable n-type doping for BP transistors via surface functionalization by atomic layer deposited magnesium oxide (MgO) with favorable controllability. By optimizing the MgO thickness, an electron mobility of up to 95.5 cm2 V-1 s-1 is reached with a simultaneous significant suppression of hole conduction. Subsequently, a high-performance complementary logic inverter is demonstrated within a single BP flake, which operates well with a supply voltage as low as <0.5 V, outperforming reported BP inverters in terms of logic level match, power consumption and process feasibility. Our findings suggest that surface charge transfer doping via MgO can be used as a promising technique towards high performance BP-based functional nanoelectronics.
A stack
consisting of atomic layer deposited (ALD) aluminum oxide
(Al2O3) and hexagonal boron nitride (h-BN) is
proposed and demonstrated as the sensing layer of extended gate ion-sensitive
field-effect transistors (EG ISFETs) in this work. The use of h-BN
in the sensing stack is to suppress the voltage drift during pH measurement
because of a low defect level inside the two-dimensional (2D) h-BN.
The use of Al2O3 in the sensing stack is to
improve the pH sensitivity due to the chemical inertness of h-BN and
the resultant low sensitivity. A low-power oxygen plasma treatment
on the surface of the h-BN flake is employed to obtain a uniform and
high-quality Al2O3 layer on top of h-BN. The
influences of Al2O3 thickness in the Al2O3/h-BN sensing stack on the sensitivity and drift
characteristics of 2D EG ISFETs are investigated. It is found that
the EG ISFET with molybdenum disulfide (MoS2) field-effect
transistor (FET) and Al2O3/h-BN sensing stack
with 5 nm thick Al2O3 provides a pH sensitivity
of >50 mV/pH while at the same time exhibiting a low drift value
of
∼4 mV/h. Moreover, a pH sensing resolution of 1.54 × 10–3 pH is extracted by using low-frequency noise measurement.
All these suggest the Al2O3/h-BN stack as a
highly promising sensing stack for high-sensitivity and low-drift
ISFETs.
Abstract-A compact coplanar waveguide fed multiband antenna is proposed and investigated. The proposed antenna consists of a rectangular radiating patch and dual meander strips with a defected ground plane. The size of the fabricated prototype is 28.3 × 24 × 1.59 mm 3 . The proposed antenna radiates at three different resonant modes, which cover 2.29-2.63 GHz, 3.26-3.96 GHz, and 4.97-6.10 GHz. The proposed antenna can be used for TD-LTE 2300/2500 (2.305-2.4 GHz), WLAN (2.4-2.4835 GHz and 5.15-5.875 GHz) and WiMAX (2.3-2.4 GHz and 3.3-3.7 GHz) applications. The proposed antenna exhibits an omnidirectional radiation pattern in the H-plane and a dipole-like radiation pattern in the E-plane. The measured peak gains are 2.64/4.48/6.08 dBi at 2.4/3.5/5.5 GHz operating frequency bands, respectively.
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