Lake Shore Cryotronics introduce SMU nano/2D semiconductor testing

As traditional semiconductor devices continue to shrink, operating at ever-lower signal levels, engineers face increasing challenges in validating these components, especially next-generation nanoscale materials. Lake Shore Cryotronics, a scientific instruments and temperature sensors manufacturer, has addressed this challenge with a test instrument specifically optimised for nanoscale and other low-power semiconductor devices.

Chuck Cimino, Senior Product Manager at Lake Shore Cryotronics, explaines: “The new SMU-10 makes highly sensitive, selective AC detection technology used in research labs conveniently available to semiconductor design and test engineers. Using the familiar four-instruments-in-one SMU format, they can easily make extremely sensitive, low-noise measurements.”

New source measure unit advances the M81-SSM platform

The SMU-10 Source Measure Unit expands Lake Shore's MeasureReady M81-SSM Synchronous Source Measure System. This new module provides engineers with the ability to source and measure signals that would typically be overwhelmed by electrical noise.

Speaking to Cimino, he tells me: “This is equivalent to putting a car on a dynamometer, then running it through its operating range. You plot your voltages and currents, and then you look at the bends and the straight parts and the magnitudes and all the data behind it.”

With shrinking device sizes, lower voltages and currents have become essential, and these new levels of miniaturisation create unique testing challenges. Each generation of devices now requires characterisation with reduced power, pushing signal levels even lower. For this reason, the M81-SSM platform has been engineered to deliver high-precision sourcing and measurement at levels that suit these advancing requirements.

The first SMU with both AC and DC sourcing and measurement capabilities

The M81-SSM’s SMU-10 module offers both AC and DC I-V characterisation capabilities with synchronous AC detection measurements. This feature is significant for engineers seeking to avoid noise while extracting small, usable signals from devices.

Cimino notes: “The SMU has got this convenience argument … whether you want to put a voltage or a current – measure voltage – it's simply a programming choice. You don't have to move wires around. You don’t have to get another instrument.”

The module also employs frequency and phase-sensitive lock-in amplifier technology, isolating the exact reference frequency of interest, which reduces interference from power line and ambient noise. The system supports a maximum signal bandwidth of up to 100kHz, enabling user-selectable frequencies to optimise testing.

Ultra-low noise performance and high sensitivity

The SMU-10 module offers extremely low source and measurement noise, offering sensitivities below 10nV/√Hz (AC) and below 100fA (DC), with voltage and current levels reaching ±10V and ±100mA DC/peak. Lake Shore has designed the module to excel in environments where signals would otherwise be buried under electrical noise.

“We’re about one-tenth of the noise [of competing instruments],” notes Cimino, emphasising the noise performance improvements in comparison to other SMUs.

The SMU-10 module, like all modules in the M81-SSM series, maintains minimal noise by placing sensitive analogue electronics close to the device under test (DUT), while digital processing occurs remotely in the main instrument. This modular architecture helps to reduce ambient, power line, and machine noise interference.

Synchronised sampling technology for precision

With Lake Shore’s patented MeasureSync technology, the M81-SSM platform synchronously samples source outputs and measures inputs at 375 kilosamples per second. This tight synchronisation prevents data misalignment and supports time-dependent measurements, a critical feature for applications like pulsed I-V measurements in nanoscale devices.

Cimino comments on the modularity and adaptability of the instrument: “It’s simple, modular. You can plug our single function modules in and out, or use these combinational four-in-one modules.”

Unique capabilities for testing emerging nanoscale technologies

The new SMU module provides comprehensive capabilities for three-terminal device testing. The M81-SSM can handle up to three SMU-10 modules, giving engineers independent control of each terminal (e.g., gate, drain, source) of a FET or similar complex semiconductor device. Cimino describes the platform’s applications for advanced materials research, particularly in atomic-scale and two-dimensional semiconductors like graphene.

Ultra-low noise source combined with ultra-sensitive measure capabilities

The SMU-10 module boasts ultra-low source noise performance and high sensitivities of below 10nV/√Hz (AC) and below 100fA (DC). This precision makes it several orders of magnitude quieter than conventional DC SMUs, ideal for nanoscale testing.

Cimino emphasises the SMU-10’s advantage in preventing damage to sensitive devices by maintaining a low-noise environment: “When you look at conventional systems, the noise can be enough to even damage nano-scale devices.”

The modular setup of the M81-SSM allows for the SMU-10 to be placed close to the device under test, reducing the length of test leads and therefore minimising ambient noise interference.

“Each needle can do all the functions under software control, so you don’t have to move wires around or get another instrument. The SMU brings both the convenience and safety needed for accurate low-level testing,” said Cimino.

Synchronised sampling for precise timing

The M81-SSM’s MeasureSync technology samples all source outputs and measures inputs at 375 kilosamples per second, providing synchronised data collection and eliminating misalignment errors. This precision timing is essential for applications like pulsed I-V measurements, reducing heat accumulation in low-power devices and making it suited for time-dependent measurements.

Advanced resistance mode and testing of three-terminal devices

In resistance measurement, the M81-SSM’s lock-in mode can compensate for phase shifts from cable capacitance, presenting a more accurate resistance measurement. The advanced AC resistance function is compatible with all M81-SSM modules, including the SMU-10. For three-terminal devices, such as FETs, the M81-SSM can independently control the gate, drain, and source terminals, enabling simultaneous monitoring and comprehensive characterisation.