摘要:
A floating gate memory device comprises a channel for conducting carriers from source to drain, a semiconductor heterostructure forming a potential well (floating gate) for confining carriers sufficiently proximate the channel so as to at least partially deplete it, and a graded bandgap injector region between the control gate and the floating gate for controlling the injection of carriers into and out of the potential well. Also described is a three element memory cell, including the memory device and two FETs, which operates from a constant, non-switched supply voltage and two-level control voltages. Arrays of memory devices may also be used to detect light in a variety of applications such as imaging.
摘要:
A floating gate memory device comprises a channel for conducting carriers from source to drain, a semiconductor heterostructure forming a potential well (floating gate) for confining carriers sufficiently proximate the channel so as to at least partially deplete it, and a graded bandgap injector region between the control gate and the floating gate for controlling the injection of carriers into and out of the potential well. Also described is a three element memory cell, including the memory device and two FETs, which operates from a constant, non-switched supply voltage and two-level control voltages. Arrays of memory devices may also be used to detect light in a variety of applications such as imaging.
摘要:
Disclosed is a manufacturing method to fabricate Heterojunction Bipolar Transistors (HBTs) that enables self-alignment of emitter and base metal contact layers with precise sub-micron spacing using a dielectric-assisted metal lift-off process. Such an HBT process relies on the formation of an “H-shaped” dielectric (i.e., Si3N4/SiO2) mask conformally deposited on top of the emitter contact metallization that is used to remove excess base metal through lift-off by a wet chemical HF-based etch. This HBT process also uses a thin selective etch-stop layer buried within the emitter layer to prevent wet chemical over-etching to the base and improves HBT reliability by forming a non-conducting, depleted ledge above the extrinsic base layer. The geometry of the self-aligned emitter and base metal contacts in the HBT insures conformal coverage of dielectric encapsulation films, preferably Si3N4 and/or SiO2, for reliable HBT emitter p-n junction passivation. Thus, the disclosed HBT process enables scaling of narrow emitter stripe widths down to sub-micron dimensions producing transistors with cut-off frequencies in the range of several hundred GigaHertz.
摘要翻译:公开了一种制造异质结双极晶体管(HBT)的制造方法,其使用介电辅助金属剥离工艺使得发射极和母材接触层能够以精确的亚微米间距自对准。 这种HBT工艺依赖于形成“H形”电介质(即,Si 3 N 4 N 2 O 3 / SiO 2)掩模 沉积在用于通过湿化学HF基蚀刻通过剥离去除多余的基体金属的发射极接触金属化的顶部。 该HBT工艺还使用掩埋在发射极层内的薄的选择性蚀刻停止层,以防止对基底的湿化学过度蚀刻,并通过在外部基极层之上形成非导电的耗尽凸缘来提高HBT的可靠性。 HBT中的自对准发射极和母体金属触点的几何形状确保电介质封装膜的适形覆盖,优选Si 3 N 4 N 2和/或SiO 2 SUB>,用于可靠的HBT发射极pn结钝化。 因此,所公开的HBT工艺能够将窄发射极条宽度缩小到亚微米尺寸,从而产生截止频率在几百千兆赫兹范围内的晶体管。
摘要:
Disclosed is a manufacturing method to fabricate Heterojunction Bipolar Transistors (HBTs) that enables self-alignment of emitter and base metal contact layers with precise sub-micron spacing using a dielectric-assisted metal lift-off process. Such an HBT process relies on the formation of an “H-shaped” dielectric (i.e., Si3N4/SiO2) mask conformally deposited on top of the emitter contact metalization that is used to remove excess base metal through lift-off by a wet chemical HF-based etch. This HBT process also uses a thin selective etch-stop layer buried within the emitter layer to prevent wet chemical over-etching to the base and improves HBT reliability by forming a non-conducting, depleted ledge above the extrinsic base layer. The geometry of the self-aligned emitter and base metal contacts in the HBT insures conformal coverage of dielectric encapsulation films, preferably Si3N4 and/or SiO2, for reliable HBT emitter p-n junction passivation. Thus, the disclosed HBT process enables scaling of narrow emitter stripe widths down to sub-micron dimensions producing transistors with cut-off frequencies in the range of several hundred GigaHertz.
摘要:
A narrow-bandwidth, high-speed infrared radiation detector is based on tunneling of photo-excited electrons out of quantum wells. Infrared radiation incident on a superlattice of doped quantum wells gives rise to intersubband resonance radiation which excites electrons from the ground state into an excited state. A photocurrent results from excited electrons tunneling out of quantum wells. Conveniently, Group III-V materials can be used in device manufacture. Preferably, quantum well potential barriers are shaped so as to facilitate resonant tunneling of photocurrents as compared with dark current. Preferred device operation is at elevated bias voltage, giving rise to enhancement of photocurrent by a quantum-well-avalanche effect.
摘要:
Single crystals of alpha aluminum phosphate of high crystal perfection arerown from seeded solutions of aluminum orthophosphate and orthophosphoric acid in such a manner as to provide direct visual observation of the crystal growth process and allow precise determination of nucleation and growth kinetics.The method involves sealing the seeded solution in clear quartz ampules, inserting the ampules into a precisely temperature controlled silicone oil bath, increasing the temperature of the silicone oil bath from ambient temperature to approximately 150 degrees C. over a three hour period, programming the temperature of the bath upward at the rate of 0.1 to 2.0 degrees C. per day for periods up to sixty days, and removing the quartz ampules from the silicone oil bath and quickly cooling and removing the crystals.
摘要:
A method to manufacture Copper Indium Gallium di Selenide (Cu(In,Ga)Se2) thin film solar cell includes evaporating elemental Cu, In, Ga, and Se flux sources onto a heated substrate in a single vacuum system to form a non-intentionally doped Cu(In,Ga)Se2 p-type conductivity layer and exposing the p-type conductivity layer to a thermally evaporated flux of Beryllium (Be) atoms to convert a surface layer of the p-type conductivity layer to an n-type conductivity layer resulting in a buried Cu(In,Ga)Se2 p-n homojunction. Also, the source of Be atoms includes a circular rod of Be having a uniform cross-section that is resistively heated and having its temperature controlled by passing an electrical current through the rod.
摘要:
36 We have discovered the III-V semiconductor layers with previously unattainably high effective hole concentrations can be produced by molecular growth processes (e.g. MBE) if an amphoteric dopant such as Be is used and if, during the growth of the highly doped III-V layer, the substrate is maintained at a temperature T.sub.g that is substantially lower than customarily used. For instance, a InGaAs layer with effective hole concentration 1.0.times.10.sup.20 cm.sup.-3 was grown at T.sub.g =450.degree. C., and a GaAs layer with effective hole concentration of 1.0.times.10.sup.20 cm.sup.-3 was grown at T.sub.g of 475.degree. C. The heavily doped III-V layers can be of device grade and can usefully be part of electronic devices such as high speed bipolar transistors.
摘要:
A single planar doped barrier diode is grown by the selective deposition of gallium arsenide using molecular beam epitaxy (MBE) in the center of a gallium arsenide dielectric waveguide member mounted on a ground plane. The waveguide member includes two portions which extend in opposite directions and terminating in respective metal to dielectric waveguide transition sections which are coupled to an RF input signal and local oscillator signal, respectively. The planar doped barrier diode operates as an intrinsic subharmonic mixer and accordingly the local oscillator signal has frequency of one half the input signal frequency. An IF output signal is coupled from the mixer diode to a microstrip transmission line formed on an insulating layer fabricated on the ground plane. Dielectric waveguide isolators are additionally included on the dielectric waveguide segments to mutually isolate the input signal and local oscillator signal. A monolithic form of circuit fabrication is thus provided which allows the planar doped barrier mixer circuit to be extremely small and the cost of mass producing such a circuit to be very economical.