Abstract:We report on a memory structure that only makes use of holes as the storage charges based on type-II GaSb/GaAs quantum dots (QDs) using an AlGaAs barrier. The C-V measurements confirm existence of quantum states in the GaSb dots and reveal the applied bias voltage range for the write/erase process by charging/discharging the QDs. A large hole activation energy value of 540 meV is obtained for the device measured by deep level transient spectroscopy. Our results indicate that type-II GaSb/GaAs QD system is a pr… Show more
“…In our previous work, we suggested a possible readout scheme for picking up this voltage change near the QD in a narrow measurement time window of picoseconds . For most of the Modes discussed in Working Modes of the Proposed SQDSPD, the output signal has a retention time equal to the trapped charge lifetime (e.g., τ 6 in Figure f), which can be as long as microseconds. , This long signal retention time helps relax significantly the tight timing requirements imposed on the readout circuit, as compared to the situation in ref . Hence, the design of the readout scheme can emphasize more on the optimization of parameters such as the amplification of the voltage signal, rather than be limited by the short readout time.…”
Section: Discussionmentioning
confidence: 99%
“…τ 5 is related to the electron transit time and is negligibly short for a small QD and a thin barrier layer; τ 6 is essentially the hole lifetime, and can be estimated with 1/Γ hs . Since Γ hs is usually small for thick barriers, τ 6 is relatively long and can be of the order of microsecond or even longer. , This long lifetime translates into a long retention time for Δ V sp6 , which helps relax the stringent requirements imposed on the timing and the speed of the measurement electronics connected to the sense probe. To speed up the reset process, a positive pulse can be applied to the gate to eliminate Δ V sp6 (yellow dashed line in Figure f) and hence bring the detector back to the initial state shown in Figure a.…”
Section: Working Modes Of the Proposed
Sqdspdmentioning
Capturing single photons through light−matter interactions is a fascinating and important topic for both fundamental research and practical applications. The light− matter interaction enables the transfer of the energy of a single photon (∼1 eV) to a bound electron, making it free to move either in the crystal lattice or in the vacuum. In conventional single photon detectors (e.g., avalanche photodiodes), this free electron triggers a carrier multiplication process which amplifies the ultraweak signal to a detectable level. Despite their popularity, the timing jitter of these conventional detectors is limited to tens of picoseconds, mainly attributed to a finite velocity of carriers drifting through the detectors.Here we propose a new type of single photon detector where a quantum dot, embedded in a single-electron transistor like device structure, traps a photogenerated charge and gives rise to a sizable voltage signal (∼7 mV per electron or hole by simulation) on a nearby sense probe through capacitive coupling (with a capacitance ∼ aF). Possible working modes of the proposed detector are theoretically examined. Owing to a small lateral dimension of the quantum dot, detailed analyses reveal that the intrinsic timing jitter of the proposed detector is in the femtosecond to subpicosecond range, and the intrinsic dark count rate is negligible up to moderately high temperatures. These figures of merit are orders of magnitude superior to those of the state-of-the-art single photon detectors work in the same spectral range, making the proposed detector promising for timing-sensitive and quantum information applications.
“…In our previous work, we suggested a possible readout scheme for picking up this voltage change near the QD in a narrow measurement time window of picoseconds . For most of the Modes discussed in Working Modes of the Proposed SQDSPD, the output signal has a retention time equal to the trapped charge lifetime (e.g., τ 6 in Figure f), which can be as long as microseconds. , This long signal retention time helps relax significantly the tight timing requirements imposed on the readout circuit, as compared to the situation in ref . Hence, the design of the readout scheme can emphasize more on the optimization of parameters such as the amplification of the voltage signal, rather than be limited by the short readout time.…”
Section: Discussionmentioning
confidence: 99%
“…τ 5 is related to the electron transit time and is negligibly short for a small QD and a thin barrier layer; τ 6 is essentially the hole lifetime, and can be estimated with 1/Γ hs . Since Γ hs is usually small for thick barriers, τ 6 is relatively long and can be of the order of microsecond or even longer. , This long lifetime translates into a long retention time for Δ V sp6 , which helps relax the stringent requirements imposed on the timing and the speed of the measurement electronics connected to the sense probe. To speed up the reset process, a positive pulse can be applied to the gate to eliminate Δ V sp6 (yellow dashed line in Figure f) and hence bring the detector back to the initial state shown in Figure a.…”
Section: Working Modes Of the Proposed
Sqdspdmentioning
Capturing single photons through light−matter interactions is a fascinating and important topic for both fundamental research and practical applications. The light− matter interaction enables the transfer of the energy of a single photon (∼1 eV) to a bound electron, making it free to move either in the crystal lattice or in the vacuum. In conventional single photon detectors (e.g., avalanche photodiodes), this free electron triggers a carrier multiplication process which amplifies the ultraweak signal to a detectable level. Despite their popularity, the timing jitter of these conventional detectors is limited to tens of picoseconds, mainly attributed to a finite velocity of carriers drifting through the detectors.Here we propose a new type of single photon detector where a quantum dot, embedded in a single-electron transistor like device structure, traps a photogenerated charge and gives rise to a sizable voltage signal (∼7 mV per electron or hole by simulation) on a nearby sense probe through capacitive coupling (with a capacitance ∼ aF). Possible working modes of the proposed detector are theoretically examined. Owing to a small lateral dimension of the quantum dot, detailed analyses reveal that the intrinsic timing jitter of the proposed detector is in the femtosecond to subpicosecond range, and the intrinsic dark count rate is negligible up to moderately high temperatures. These figures of merit are orders of magnitude superior to those of the state-of-the-art single photon detectors work in the same spectral range, making the proposed detector promising for timing-sensitive and quantum information applications.
“…A tightly packed array of tiny islands, each around 15 nm across, could store 1 terabyte (1,000 GB) of data per square inch, the researchers say. Dieter Bimberg and colleagues at the Technical University of Berlin, Germany, with collaborators at Istanbul University, Turkey, demonstrated that it is possible to write information to the quantum dots in just 6 ns [ 165 , 166 ]. The key advantages of quantum dot (QD) NVMs are the high read/write speed, small size, low operating voltage, and, most importantly, multibit storage per device.…”
Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new class of memory technologies and scaling of scientific procedures based on an investigation of recent progress in advanced Flash memory devices.
“…Semiconductor quantum dots (QDs) have become more and more fascinating nanoscopic structures due to their increasing demand in information storage in non-volatile memory (NVM) applications. [1][2][3] NVM devices are used as a main component in all types of portable electronic gadgets such as solid state disks, smart phones, tablet PCs, etc. Most of the commercially available memory devices consist of a metal-oxide-semiconductor (MOS) structure.…”
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