Ambipolar Black Phosphorus MOSFETs With Record n-Channel Transconductance

Ambipolar black phosphorus MOSFETs with record n-channel extrinsic transconductance are reported. The devices consist of multilayer black phosphorus aligned to a local back-gate electrode with 10-nm-thick HfO
₂
gate dielectric. Before passivation, devices with 0.3-
$\mu \text{m}$
gate length behaved as p-MOSFETs with peak extrinsic transconductance,
$g_{m}$
, of 282
$\mu \text{S}/\mu \text{m}$
at
$V_{\textrm {DS}}=- 2$
V. After passivation, the same devices displayed the ambipolar behavior, and when tested as n-MOSFETs, had peak
$g_{m} =66~\mu \text{S}/\mu \text{m}$
at
$V_{\textrm {DS}} = +2$
V, and similar devices on the same wafer had
$g_{m}$
as high as 80
$\mu \text{S}/\mu \text{m}$
. These results are an important step toward the realization of high-performance black phosphorus complementary logic circuits.