Ultrathin dielectric capping layers are a prominent route for threshold voltage control in advanced Si devices. In this work the position of an Al2O3 layer inside a HfO2-based stack is systematically varied and investigated following a low and a high temperature anneal. Electrical results are compared with a sub-nanometer resolution materials characterization, showing a diffusion of Al to the bottom HfO2 interface. A correlation is found between the presence of Al at the bottom interface and a flatband voltage increase. Based on these findings, we propose to use the position of the Al2O3 for fine-tuning the threshold voltage.

We demonstrate a low voltage nonvolatile memory field effect transistor comprising thermal SiO2 tunneling and HfO2 blocking layers as the gate dielectric stack and Au nanocrystals as charge storage nodes. The structure exhibits a memory window of ∼2 V at an applied sweeping voltage of ±3 V which increases to 12.6 at ±12 V. Retention tests show an extrapolated loss of 16% after ten years in the hysteresis width of the threshold voltage. Dynamic program/erase operation reveal an approximately pulse width independent memory for pulse durations of 1 μs to 10 ms; longer pulses increase the memory window while for pulses shorter than 1 μs, the memory windows vanishes. The effective oxide thickness is below 10 nm with very low gate and drain leakage currents.

We present a metal-insulator-semiconductor nonvolatile memory capacitor based on two gold nanoparticle charge storage layers, two HfO2 layers, and a multilayer HfNO/HfTiO stack. The device exhibits an equivalent oxide thickness of 7.3 nm, a hysteresis of 15 V at a gate voltage of +11 to −8 V, and a storage charge density of 2.75×1013cm−2 . A leakage of 3.6×10−5A/cm2 at −10 V, a breakdown voltage of 13.3 V, and good retention properties with a hysteresis window of 10 V following more than 10 h of consecutive write/erase operations with a ±7 V swing were demonstrated. The capacitor characteristics are frequency-independent in the 10 kHz–1 MHz range.

We describe the effect of optical excitation of state of the art nonvolatile memory capacitors. The devices comprise Au nanocrystals sandwiched between a SiO2 tunneling layer and a HfO2 blocking layer and exhibit an effective oxide thickness of 7.5 nm. The memory properties are modified by the optical excitation due to nonequilibrium depletion. Optical control with different illumination wavelengths as well as variable optical intensities and pulse widths is described.

We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology.