Phosphorus Ion Implantation Research Articles

Size and dopant-concentration dependence of photoluminescence properties of ion-implanted phosphorus- and boron-codoped Si nanocrystals

Size and dopant-concentration dependence of photoluminescence properties of ion-implanted phosphorus- and boron-codoped Si nanocrystals

Effect of phosphorus ion implantation on back gate effect of partially depleted SOI NMOS under total dose radiation

The mechanism of improving the TID radiation hardened ability of partially depleted silicon-on-insulator (SOI) devices by using the back-gate phosphorus ion implantation technology is studied. The electron traps introduced in SiO2 near back SiO2/Si interface by phosphorus ions implantation can offset positive trapped charges near the back-gate interface. The implanted high concentration phosphorus ions can greatly reduce the back-gate effect of a partially depleted SOI NMOS device, and anti-total-dose radiation ability can reach the level of 1 Mrad(Si) for experimental devices.

On the ion implantation of phosphorus as a method for the passivation of states at the interface between 4H-SiC and SiO2 produced by thermal oxidation in dry oxygen

A method is suggested for reducing the density of surface states at the 4H-SiC/SiO2 interface by the implantation of phosphorus ions into a 4H-SiC epitaxial layer immediately before the growth of a gate insulator in an atmosphere of dry oxygen. A significant decrease in the density of surface states is observed at a phosphor-ion concentration at the SiO2/SiC interface exceeding 1018 cm−3. However, together with the passivation of surface states, the introduction of phosphorus ions leads to an increase in the built-in charge in the insulator and also slightly deteriorates the reliability of the gate insulator fabricated by this technique.

Towards simultaneous achievement of carrier activation and crystallinity in Ge and GeSn with heated phosphorus ion implantation: An optical study

We have investigated the optical properties of Ge and GeSn alloys implanted with phosphorus ions at 400 °C by spectroscopic ellipsometry from far-infrared to ultraviolet. The dielectric response of heated GeSn implants displays structural and transport properties similar to those of heated Ge implants. The far-infrared dielectric function of as-implanted Ge and GeSn shows the typical free carrier response which can be described by a single Drude oscillator. Bulk Ge-like critical points E1, E1 + Δ1, E0', and E2 are observed in the visible-UV dielectric function of heated Ge and GeSn indicating single crystalline quality of the as-implanted layers. Although the implantation at 400 °C recovers crystallinity in both Ge and GeSn, an annealing step is necessary to enhance the carrier activation.

Passive charge state control of nitrogen‐vacancy centres in diamond using phosphorous and boron doping

The control and stabilisation of the charge state of nitrogen‐vacancy centres in diamond is an important issue for the achievement of reliable processing of spin‐based quantum information. The effect of phosphorous and boron doping of diamond on the charge state of nitrogen‐vacancy (NV) centres is shown here. Ensembles of NV centres are produced at a depth of 60 nm in ultrapure diamond by implantation of nitrogen ions. Overlapping with the NV ensembles, donor and acceptor doped regions of different doping levels are prepared by ion implantation of phosphorus and boron followed by annealing in vacuum at 1500 °C. We show how the charge state of NV centres is controlled by the presence of phosphorous or boron atoms in their neighbourhood. For the lowest doping level, spectral measurements on the ensemble of NV centres reveal a higher amount of NV0 in the case of boron and a higher amount of NV− in the case of phosphorus, as compared with undoped regions. This behaviour is strengthened when the doping level is increased. Interestingly, the charge state control of native silicon‐vacancy centres is also evidenced. Finally, we discuss the role of the surface termination of diamond on the average charge state of the NV ensemble (still dominant even at a depth of 60 nm) and confirm that the surface 2D‐hole‐gas (H‐termination) can be compensated by nitrogen itself.

Effect of Thermal Annealing on the Characteristics of Phosphorus-Implanted ZnO Crystals

A P-doped ZnO surface layer on undoped ZnO wafers was prepared by phosphorus (P) ion implantation. Hall effect measurement revealed p-type conduction in such layers annealed at 800°C. This indicates that acceptor levels are present in P-doped ZnO, even though the ZnO is still n-type. Micro-Raman scattering in −z(xy)z geometry was conducted on P-implanted ZnO. The E 2 high mode shift observed toward the high-energy region was related to compressive stress as a result of P-ion implantation. This compressive stress led to the appearance of an A 1(LO) peak, which is an inactive mode. This A 1(LO) peak relaxed during thermal annealing in ambient oxygen at temperatures higher than 700°C. The P2p3/2 peak observed at 135.6 eV by x-ray photoelectron spectroscopy is associated with chemical bond formation leading to 2(P2O5) molecules. This indicates that implanted P ions substituted Zn sites in the ZnO layer. In photoluminescence spectroscopy, the P-related peaks observed at energies ranging between 3.1 and 3.5 eV originated from (A0, X) emission, because of PZn-2VZn complexes acting as shallow acceptors. The acceptor level was observed to be 126.9 meV above the valence band edge. Observation of this P-related emission indicates that ion implantation results in acceptor levels in the P-doped ZnO layer. This suggests that the P2O5 bonds are responsible for the p-type activity of P-implanted ZnO.

High efficiency large area n -type front junction silicon solar cells with boron emitter formed by screen printing technology

In this paper, we report on commercially viable screen printing (SP) technology to form boron emitters. A screen-printed boron emitter and ion-implanted phosphorus back surface field were formed simultaneously by a co-annealing process. Front and back surfaces were passivated by chemically grown oxide capped with plasma-enhanced chemical vapor deposition silicon nitride stack. Front and back contacts were formed by traditional SP and firing processes with silver/aluminum grid on front and local silver back contacts on the rear. This resulted in 19.6% efficient large area (239 cm2) n-type solar cells with an open-circuit voltage Voc of 645 mV, short-circuit current density Jsc of 38.6 mA/cm2, and fill factor of 78.6%. This demonstrates the potential of this novel technology for production of low-cost high-efficiency n-type silicon solar cells. Copyright © 2014 John Wiley & Sons, Ltd.

On a feature of temperature dependence of contact resistivity for ohmic contacts to n-Si with an n + -n doping step

We present both theoretical and experimental temperature dependences of contact resistivity ρс(Т) for ohmic contacts to the silicon n + -n-structures whose n + -layer was formed using phosphorus diffusion or ion implantation. The ρс(Т) dependence was measured in the 125-375 K temperature range with the transmission line method, with allowance made for conduction in both the n + -layer and n + -n doping step.

Influence of P<sup>+</sup>-Implantation and Post-Annealing on Warpage Structure of 4H-SiC Wafers

We examined the warpage structure in epitaxial 4H-SiC wafers subjected to phosphorus-ion (P+) implantation and post-annealing with varying implantation and annealing temperatures, using glazing-incidence monochromatic synchrotron X-ray topography. Using Raman spectroscopy, we then studied the relationship between the warpage of the crystal plane in the underlying epilayer and the recovery of lattice disorder in the implanted layer. We determined that the warpage structure of the underlying SiC epilayer was closely correlated with the recovery of lattice disorder in the implanted layer.

Point defect engineering study of phosphorus ion implanted germanium

AbstractWe present experimental results on shallow junction formation in germanium by phosphorus ion implantation and standard rapid thermal processing. An attempt is made to improve phosphorus electrical activation using point defect engineering method by introducing an excess of point defects in germanium prior to the phosphorus implantation. The focus is on studying the phosphorus activation and diffusion as a function of germanium co‐implant energy. Hall Effect and Secondary Ion Mass Spectrometry (SIMS) measurements are employed for characterisation of phosphorus activation and diffusion, respectively. Phosphorus activation was improved at higher annealing temperature for the implants with germanium co‐implant. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Carriers' localization and thermal redistribution in post growth voluntarily tuned quantum dashes' size/composition distribution

This paper treats the impact of post growth tuned InAs/InP quantum dashes' (QDas) size/composition distribution on carriers' localization and thermal redistribution. The spread of this distribution depends on the experimental conditions used for the phosphorus ion implantation enhanced intermixing process. Atypical temperature-dependent luminescence properties have been observed and found to be strongly dependent on the amount of QDas size/composition dispersion. The experimental results have been reproduced by a model that takes into account the width of the QDas localized states distribution and consequent thermally induced carriers' redistribution. This model gives critical temperature values marking the beginning and the end of carriers delocalization and thermal transfer processes via an intermixing induced carrier's transfer channel located below the wetting layer states.

Bandgap Control for Intersubband Transition in InGaAs/AlAsSb Coupled Double Quantum Wells

This letter demonstrates bandgap control of ion-induced intermixing on InGaAs/AlAsSb coupled double quantum wells (CDQWs). With phosphorus ion implantation and different rapid thermal annealing (RTA) processes, the blueshift of the bandgap profile can be tailored. The influence of quantum well intermixing on the cross-phase modulation (XPM), caused by the intersubband transition in the CDQWs, is also experimentally investigated. Higher RTA temperature or longer annealing time could cause a larger bandgap blueshift that decreases the XPM efficiency. After annealing, the implanted CDQWs have a relatively low transmission loss, whereas the non-implanted sample can maintain a high XPM efficiency. This result can be used for monolithic integration of different bandgap modules with spatially selective mannerisms, and the implications are vast for optical communication applications.

Band edge tailoring of InGaAs/AlAsSb coupled double quantum wells for a monolithically integrated all-optical switch

We demonstrate a compact all-optical Michelson interferometer (MI) gating switch with monolithic integration of two different bandgap energies. Based on the ion-induced intermixing in InGaAs/AlAsSb coupled double quantum wells, the blueshift of the band edge can be tailored. Through phosphorus ion implantation with a dose of 5 × 10(14) cm(-2) and subsequent annealing at 720 °C for 60 s, an implanted sample can acquire a high transmittance compared with the as-grown one. Meanwhile, the cross-phase modulation (XPM) efficiency of a non-implanted sample undergoing the same annealing process decreases little. An implanted part for signal propagation and a non-implanted section for XPM are thus monolithically integrated for an MI switch by an area-selective manner. Full switching of a π-rad nonlinear phase shift is achieved with pump pulse energy of 5.6 pJ at a 10-GHz repetition rate.

Improved electrical characteristics of porous germanium photodiode obtained by phosphorus ion implantation

Germanium–based photodetectors are the standard technology used for radiometric measurement in the IR spectral range. Shallow PN+ junctions were obtained by using ion implantation in p–type germanium. N–type doping was achieved by phosphorus implantation at a dose of 1 × 1015 cm−2 doses and an energy of 150 keV followed by annealing at 600°C for 2 h. In order for the new detector to be used as a standard for radiometric measurement, a porous layer is introduced on the active surface. After metallisation by thermal evaporation of indium (In) on the front side and gold (Au) on the back side, the new porous germanium–based photodetector is essentially done. The electrical behaviour of this porous germanium photodiode is characterised by current–voltage measurements that are compared to the I–V characteristic of classical germanium photodiodes. The results of this study show a huge increase of the photocurrent, a significant increase of the shunt resistance and low series resistance. Effects of low shunt resistance are also discussed. AFM showed that the porous layer contributes to trap the incident optical radiation and to reduce the reflection coefficient fluctuations of the front face of the photodiode.

Silver Contact Grid: Inferred Contact Resistivity and Cost Minimization in 19% Silicon Solar Cells

The analysis of silicon solar cell contacts having an H-bar front grid pattern is extended by enabling the contact resistivity to be inferred from the measurement of total series resistance and the determination of six individual components of series resistance. Analysis of the contact system was completed for a representative 19% cell fabricated from a 156-mm pseudosquare p-Cz wafer using standard production processes, including phosphorus ion implantation, thermal oxide surface passivation, silicon nitride deposition, and screen-printing and firing of front silver gridlines and busbars, back silver soldering pads, and back aluminum contact. Gridline width was measured to be 80 μm after firing, with an average thickness of 7.4 μm and an effective resistivity of 4.7 μΩ·cm. Contact resistivity to the uniform 91 Ω/ <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\square$</tex></formula> emitter was inferred to be 5.3 mΩ·cm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{2}$</tex></formula> from the total series resistance and its components. Using these values, gridline spacing was optimized for maximum efficiency (1.7 mm, 91 lines, 19.1%, $0.040/W) or minimum silver cost (2.1 mm, 74 lines, 19.0%, $0.038/W). The analysis methodology was further applied to examine the impact of gridline width and silver pricing on cell efficiency and incremental cost. Such analysis can serve as a guideline for future contact system designs when the cost of silver changes or when printing technology allows narrower lines.

Effect of phosphorus ion implantation on the optical properties of thin films of germanium dioxide doped with Er3+ and Yb3+ ions

It is shown that the ion implantation of phosphorus into thin amorphous films of germanium dioxide doped with Er3+ and Yb3+ ions can be used for enhancing luminescence from Er3+ ions at ∼1.53 μm.

Nickel ohmic contacts of high-concentration P-implanted 4H-SiC

Different-dose phosphorus ion implantation into 4H-SiC followed by high-temperature annealing was investigated. AlN/BN and graphite post-implantation annealing for ion-implanted SiC at 1650 °C for 30 min was conducted to electrically activate the implanted P+ ions. Ni contacts to the P+-implanted 4H-SiC layers were examined by transmission line model and Hall measurements fabricated on P-implanted (0001). The results indicated that a high-quality ohmic contact and specific contact resistivity of 1.30 × 10−6 Ω · cm2 was obtained for the P+-implanted 4H-SiC layers. The ρC values of the Ni-based implanted layers decreased with increasing P doping concentrations, and a weaker temperature dependence was observed for different samples in the 200–500 K temperature range.

Diamond based light-emitting diode for visible single-photon emission at room temperature

Diamond-based p-i-n light-emitting diodes capable of single-photon emission in the visible spectral region at room temperature are discussed. The diodes were fabricated on a high quality single crystal diamond grown by chemical vapor deposition. Implantation of boron and phosphorus ions followed by annealing at a temperature of 1600 °C has been used for doping p-type and n-type areas, respectively. Electrical characterization of the devices demonstrates clear diode behavior. Spectra of electroluminescence generated in the i-area reveal sole emission from the neutral nitrogen-vacancy (NV) defects. Photon antibunching implies single-photon character of this emission when generated by individual NV defects.

Bound exciton photoluminescence from ion‑implanted phosphorus in thin silicon layers

We report the observation of clear bound exciton (BE) emission from ion-implanted phosphorus. Shallow implantation and high-temperature annealing successfully introduce active donors into thin silicon layers. The BE emission at a wavelength of 1079 nm shows that a part of the implanted donors are definitely activated and isolated from each other. However, photoluminescence and electron spin resonance studies find a cluster state of the activated donors. The BE emission is suppressed by this cluster state rather than the nonradiative processes caused by ion implantation. Our results provide important information about ion implantation for doping quantum devices with phosphorus quantum bits.

Phosphorus ion implantation and annealing induced n-type conductivity and microstructure evolution in ultrananocrystalline diamond films

We report n-type conductivity in phosphorus ion implanted ultrananocrystalline diamond films annealed at 800 °C and above. The amorphous carbon transits to diamond with an increase of stress after 900 °C annealing, which exhibits lower resistivity with Hall mobility of 143 cm2/Vs. After 1000 °C annealing, the diamond transits to amorphous carbon with the stress release, which has higher carrier concentration and lower Hall mobility. Both P+-implanted nano-sized diamond grains and amorphous carbon give contributions to the n-type conductivity in the films. The microstructure evolution and electrical properties are relative to the hydrogen diffusion and desorption under high temperature annealing.