Nanoscale p-n junction fabrication in silicon due to controlled dopant electromigration

An external electric field (up to 10(6) V/cm) was used for nanoscale p-n junction fabrication in Si doped with Li (Si:Li) in situ in a scanning probe microscope. Creation of nano-p-n junctions was ascribed to the thermally assisted electromigration of Li+ ions. Tunneling I-V spectroscopy provided evidence for a conversion of the electrical conductivity type from p to n. A local temperature increase during an electric field-induced p-n junction fabrication was estimated to be up to 160 degreesC

Method and System for Performance Improvement of Photodetectors and Solar Cells

The subject of this invention are method and system for enhancing performance characteristics (quantum efficiency, photoresponse, and spectral range) in photon detectors and solar cells (both of which are referred to as photon devices). The photon detectors are p-n junctions and/or Schottky barrier diodes. The solar cells are p-n junctions. The method and system can include injecting electrons into a p-region of a photon detector or solar cell over a selected time period of up to approximately 1500 seconds to control and improve minority carrier transport, in particular a diffusion length. The injection of electrons can occur periodically over several days and can occur under a o forward bias of the p-n junction or Schottky barrier. Improvements in quantum efficiency can be between approximately 2 to approximately 5 fold. The performance output of the device can be automatically sensed with computer type logic circuits, to actively control in real time the electron injection and to maximize performance results

Study of temperature dependence for the electron injection-induced effects in GaN

Electron-beam injection-induced increase of minority carrier diffusion length in p-type GaN was studied as a function of sample temperature ranging from 25 degreesC to 130 degreesC. It was found that the rate for diffusion length increase exponentially decays with increasing temperature. This decay was attributed to a temperature-activated release of electron-beam injected electrons trapped on Mg levels. The activation energy of these levels was found to be similar to178 meV. This is in good agreement with the previously reported position for Mg levels in the GaN band gap

Cathodoluminescence studies of the electron injection-induced effects in GaN

Local irradiation of p-type GaN with the electron beam of a scanning electron microscope resulted in up to a threefold decrease of the peak cathodoluminescence intensity at similar to379 nm, as was observed in the variable temperature measurements. The cathodoluminescence results are consistent with an increase of the minority carrier diffusion length in the material, as is evident from the electron-beam-induced current measurements. The activation energy for the electron injection effect, estimated from the temperature-dependent cathodoluminescence, is in agreement with the thermal ionization energy of the Mg-acceptor in GaN

Influence of electron injection on performance of GaN photodetectors

It is demonstrated that short-time (up to 1200 s) electron injection into the p-region of GaN p-n junction, as a result of forward bias application, leads to a long-term multifold enhancement of the device peak responsivity as well as to a spectral broadening of the photoresponse. The effect is found to persist for several days and is related to an increased minority carrier diffusion length in the p region, due to an injected electron trapping on deep levels associated with Mg acceptors

Electron injection-induced effects in Mn-doped GaN

Electron injection into Mn-doped GaN resulted in pronounced changes in the minority carrier diffusion length and cathodoluminescence. In particular, multiple-fold decrease of the band-to-band cathodoluminescence intensity was observed in the temperature between -50 and 80degreesC. This decrease was accompanied by an increase of the minority carrier diffusion length in the material, measured by electron-beam-induced current. Temperature-dependent cathodoluminescence measurements revealed a recovery of the cathodoluminescence intensity with an activation energy of 360 meV

ZnO homojunction photodiodes based on Sb-doped p-type nanowire array and n-type film for ultraviolet detection

ZnO p-n homojunctions based on Sb-doped p-type nanowire array and n-type film were grown by combining chemical vapor deposition (for nanowires) with molecular-beam epitaxy (for film). Indium tin oxide and Ti/Au were used as contacts to the ZnO nanowires and film, respectively. Characteristics of field-effect transistors using ZnO nanowires as channels indicate p-type conductivity of the nanowires. Electron beam induced current profiling confirmed the existence of ZnO p-n homojunction. Rectifying I-V characteristic showed a turn-on voltage of around 3 V. Very good response to ultraviolet light illumination was observed from photocurrent measurements

Two-Color Infrared Sensor on the PbTe: In p-n Junction

A lead telluride sensor was fabricated on the base of a p-n PbTe junction created on a PbTe single crystal grown by the Czochralski technique, followed by the diffusion of an indium donor impurity into a crystal. The capacitance-voltage and current-voltage characteristics of the sensor were measured over the temperature range from 80 K to 150 K. A prototype of a high-temperature mid-IR sensor, a PbTe diode, with a cut-off wavelength of 4 μm, operating at temperatures up to 150 K, was demonstrated for the first time. The advantage of the sensor is that its operating temperature is high enough to be reached by a solid-state thermoelectric cooler. The sensor showed a specific detectivity value of 1010 cm Hz1/2/W at a temperature of 150 K and a wavelength of 4.2 μm. The possibility to sense pulses of long-IR radiation by means of the PbTe diode was also demonstrated over the 100–180 K temperature range. For the first time, a two-photon absorption-caused photovoltaic effect was observed in PbTe at a wavelength of 9.5 μm at 150 K.This article belongs to the Section Optical Sensor

Infrared detectors based on semiconductor p-n junction of PbSe

P-n junctions based on physical vapor deposition of thin PbSe films and conductivity type inversion from n- to p-type are developed and characterized over a wide range of temperatures and bias voltages. Photosensitivity and diode characteristics in the thin film PbSe diode structures were found at temperatures up to 300 K. The values of the measured and estimated parameters of these structures demonstrate their high photodetector performance and the potential for development of IR detectors with optimal sensitivity at the highest possible operating temperature