Operando atomic force microscopy (AFM) has emerged as a powerful tool for investigating semiconductor materials under controlled environmental conditions. This technique enables real-time, high-resolution imaging and property measurements while the sample is subjected to variables such as temperature, gas exposure, and humidity. Unlike in-situ electron microscopy, operando AFM avoids high-vacuum constraints and electron beam effects, making it particularly suitable for studying dynamic processes in semiconductors under realistic operating conditions.

A key advantage of operando AFM is its ability to correlate morphological changes with functional performance. For example, in semiconductor corrosion studies, researchers can monitor surface roughening, pit formation, and passivation layer growth while simultaneously measuring electrochemical activity. The AFM probe can track topographical evolution at nanometer resolution while environmental cells control corrosive agents such as moisture or reactive gases. Studies have shown that localized corrosion initiation in silicon and III-V compounds can be detected at sub-100 nm scales before macroscopic failure occurs.

Oxidation processes in semiconductors are another area where operando AFM provides critical insights. By heating samples in controlled oxygen atmospheres, researchers have observed the nucleation and growth of oxide layers on materials like silicon, germanium, and gallium arsenide. The technique reveals kinetics of oxide island formation, layer-by-layer growth, and stress-induced cracking. For silicon at elevated temperatures, operando AFM has quantified oxide growth rates that align with Deal-Grove model predictions while also capturing localized deviations caused by defects.

Device degradation studies benefit significantly from operando AFM’s ability to link structural changes to electrical or optical performance. In organic semiconductors, for instance, humidity-induced swelling and delamination can be tracked alongside mobility degradation. For inorganic devices, bias-stress experiments under controlled atmospheres have visualized charge trapping sites and dielectric breakdown precursors. One study on GaN high-electron-mobility transistors used heated operando AFM to correlate surface oxidation with threshold voltage shifts, identifying temperature-dependent degradation mechanisms.

Environmental control in operando AFM is achieved through specialized sample stages that integrate gas flow, heating, and humidity regulation. These stages maintain stability while allowing the AFM probe to scan without interference. Temperature control ranges from cryogenic to over 500°C in some systems, enabling studies of phase transitions or thermal degradation. Gas delivery systems can switch between inert, oxidizing, or reducing atmospheres, with some setups allowing sub-second gas switching for kinetic studies. Humidity control is typically achieved with mixed gas streams or piezoelectric vapor generators, capable of maintaining relative humidity from near-zero to 95% with ±1% precision.

Quantitative measurements in operando AFM extend beyond topography. Conducting-AFM modes map local current variations under environmental stimuli, revealing how gas exposure or moisture affects charge transport. Kelvin probe force microscopy (KPFM) tracks work function changes during oxidation or corrosion, providing contact potential difference maps with millivolt resolution. Mechanical properties like modulus and adhesion are measurable through force-distance curves, which have been used to study hydration-induced softening in organic semiconductors or oxide embrittlement in high-temperature environments.

Challenges in operando AFM include minimizing thermal drift during heating experiments and avoiding probe contamination in reactive atmospheres. Drift compensation algorithms and closed-loop scanner designs have improved stability, while inert probe coatings reduce unwanted reactions. Another consideration is the trade-off between environmental control and measurement speed; faster processes may require specialized high-speed AFM systems to capture dynamics adequately.

Applications in photovoltaic research demonstrate operando AFM’s versatility. Perovskite solar cells have been studied under controlled humidity to observe moisture-induced grain boundary degradation and phase segregation. In silicon heterojunction cells, operando AFM has mapped potential fluctuations at the amorphous-crystalline interface under light and bias, revealing recombination-active defects. These studies provide direct evidence of degradation pathways that inform more stable device designs.

Wide-bandgap semiconductors like SiC and GaN are increasingly studied using operando AFM for high-temperature and high-power applications. Researchers have visualized defect-mediated oxidation in SiC at 400°C, showing how step edges and dislocations accelerate oxide growth. For GaN-based devices, operando KPFM has identified surface states that contribute to current collapse during RF operation. Such insights are difficult to obtain with ex-situ techniques or electron microscopy due to the need for atmospheric pressure or high-temperature conditions.

Future developments in operando AFM may include tighter integration with other characterization methods, such as optical spectroscopy or mass spectrometry, to provide multimodal insights. Advanced probe designs could enable simultaneous thermal and electrical measurements at higher speeds. As semiconductor devices push into more extreme environments, from space applications to biological interfaces, operando AFM will remain indispensable for understanding degradation and optimizing reliability.

The technique’s non-destructive nature and compatibility with diverse environments make it uniquely suited for semiconductor research. By bridging the gap between idealized laboratory studies and real-world operating conditions, operando AFM continues to uncover mechanisms that govern performance and failure in semiconductor materials and devices. Its applications in corrosion, oxidation, and degradation studies are not only advancing fundamental understanding but also guiding the development of more robust technologies.