Effect of Si doping on the photoluminescence properties of AlGaInP/GaInP multiple quantum wells

The influence of Si doping on the photoluminescence (PL) properties of (Al_0.3Ga_0.7)_0.5In_0.5P/Ga_0.5In_0.5P multiple-quantum-wells (MQWs) was studied. For the samples without p-type layers, the PL peak wavelength from (Al_0.3Ga_0.7)_0.5In_0.5P/Ga_0.5In_0.5P MQWs did not vary when Si was doped in MQWs, the PL peak intensity did not change obviously and the PL FWHM broadened. We consider that Si doping results in worse interface quality of (Al_0.3Ga_0.7)_0.5In_0.5P/Ga_0.5In_0.5P MQWs. However, for the full light-emitting diode (LED) structure samples, the PL intensity of MQWs obviously increased when Si was doped in MQWs. The PL intensity from MQWs with Si-doped barriers was about 13 times stronger than that of undoped MQWs. The PL intensity from MQWs with Si-doped barriers and wells was strong as 28 times as that of undoped MQWs. The reasons are discussed.     

Gallium distribution and electrical activation in Ga+-implanted Si

Gallium distribution profiles in Ga⁺-implanted silicon have been measured by secondary ion mass spectrometry (SIMS) and differential Hall effect methods. The previously reported penetrating tails are not observed for as-implanted samples. The redistribution of Ga during annealing is affected by ion damage and effects due to recrystallization of the amorphous layer. Electrical carrier profiles indicate that carrier concentration higher than the usual Ga solid solubility can be achieved in Ga-implanted Si recrystallized at 600‡C. However, this large acceptor concentration diminishes after higher temperature annealing. For 900‡C anneals, the carrier concentration is limited by the Ga solid solubility and some compensation due to unannealed ion damage. Work Supported by the Joint Service Electronics Program (U.S. Army, U.S. Navy, U.S. Air Force) under Contracts DAAB-07-72-C-0259 and DAAG-16-78-C-0016, and by the National Science Foundation under Grants DMR-77-22228, DMR-76-01058, and CHE-76-03694.     

Ar^＋注入多孔硅与Ar^＋注入硅多孔结构的光致发光研究

研究了中等能量(30 key)Ar+注入多孔硅和中等能量(30 key)Ar+先注入单晶硅后再进行电化学腐蚀成的多孔结构的光致发光特性.研究结果表明:中等能量(30 key)Ar+注入多孔硅后,多孔硅原有的发光峰消失,主要是Ar+对多孔硅表面氧的剥离作用.使得与氧相关发光的结构消失,多孔硅不再发光;中等能量(30 kev)Ar+先注入单晶硅后冉电化学腐蚀成的多孔结构中,通常多孔硅原有的580 nIn附近发光峰强度随注入Ar+剂量的增加而增强,并有红移;同时在谱峰处于470 nm附近的微弱发光峰不因注入Ar+而明显变化.     

Enhanced photoluminescence from porous silicon microcavities by rare earth doping

The photoluminescence (PL) properties of porous silicon microcavities (PSMs) in the visible range at room temperature are improved by doping the rare earth ytterbium (Yb) into PSMs prepared by the electrochemical etching method. It is observed that PSMs doped with the rare earth have an emission band around 630 nm. Compared with the single-layer porous silicon (PS) film, the PSMs doped with Yb have narrower and stronger PL spectrum.     

硅中注H~+的退火行为及智能剥离SOI新材料的微结构分析

将中等剂量的H+注入到硅单晶中，并结合硅片低温键合及后续热处理形成了智能剥离SOI新材料。用热波分析技术对注H+片的剥离现象进行了无损非接触检测研究。采用剖面透射电子显微镜与高分辨率透射电子显微镜等手段对这种SOI材料的微结构进行了分析。研究表明，智能剥离SOI是一种可通过较简单的工艺获得高质量SOI材料的新途径。     

Effect of ion dose and annealing mode on photoluminescence from SiO2 implanted with Si ions

This paper discusses the photoluminescence spectra of 500-nm-thick layers of SiO₂ implanted with Si ions at doses of 1.6×10¹⁶, 4×10¹⁶, and 1.6×10¹⁷ cm⁻² and then annealed in the steady-state region (30 min) and pulsed regime (1 s and 20 ms). Structural changes were monitored by high-resolution electron microscopy and Raman scattering. It was found that when the ion dose was decreased from 4×10¹⁶ cm⁻² to 1.6×10¹⁶ cm⁻², generation of centers that luminesce weakly in the visible ceased. Moreover, subsequent anneals no longer led to the formation of silicon nanocrystallites or centers that luminesce strongly in the infrared. Annealing after heavy ion doses affected the photoluminescence spectrum in the following ways, depending on the anneal temperature: growth (up to ∼700 °C), quenching (at 800–900 °C), and the appearance of a very intense photoluminescence band near 820 nm (at >900 °C). The last stage corresponds to the appearance of Si nanocrystallites. The dose dependence is explained by a loss of stability brought on by segregation of Si from SiO₂ and interactions between the excess Si atoms, which form percolation clusters. At low heating levels, the distinctive features of the anneals originate predominantly with the percolation Si clusters; above ∼700 °C these clusters are converted into amorphous Si-phase nanoprecipitates, which emit no photoluminescence. At temperatures above 900 °C the Si nanocrystallites that form emit in a strong luminescence band because of the quantum-well effect. The difference between the rates of percolation and conversion of the clusters into nanoprecipitates allows the precipitation of Si to be controlled by combinations of these annealings. Fiz. Tekh. Poluprovodn. 32, 1371–1377 (November 1998)     

Effect of gamma irradiation on the photoluminescence of porous silicon

The effect of gamma irradiation on the luminescence properties of porous silicon produced by the electrochemical technique is studied. Changes in the photoluminescence intensity between irradiation doses and over a period of several days after the last irradiation are recorded. The quenching of photoluminescence at low irradiation doses and recovery after further irradiation are registered. It is found that porous silicon is strongly oxidized after gamma irradiation and the oxidation process continues for several days after irradiation. It is conceived that the change in the photoluminescence spectra and intensity of porous silicon after gamma irradiation is caused by a change in the passivation type of the porous surface: instead of hydrogen passivation, more stable oxygen passivation is observed. To stabilize the photoluminescence spectra of porous silicon, the use of fullerenes is proposed. No considerable changes in the photoluminescence spectra during irradiation and up to 18 days after irradiation are detected in a porous silicon sample with a thermally deposited fullerene layer. It is shown that porous silicon samples with a deposited C₆₀ layer are stable to gamma irradiation and oxidation.     

Effect of annealing on photoluminescence of passivated porous silicon

Photoluminescence (PL) of annealed porous silicon (PS) without and with nitrogen passivation has been investigated. The un-nitridated PS emits intense blue and green light, while that with passivation, emits only blue light and its intensity increases obviously. It is found that the PL intensity of the nitrified PS decreases with increasing temperature from 300 °C to 700 °C, but increases drastically after annealing at 800 °C and 900 °C, which might be due to the formation of Si–N bonds that passivates the non-radiative centers (Si dangling bonds) on the surface of PS samples. However, the intensity of the un-nitridated PS decreases continuously with increasing temperature from 300 °C to 900 °C, which might be due to desorption of hydrogen.     

Effect of a fullerene coating on the photoluminescence of porous silicon

The interaction of a matrix of silicon nanocrystallites (porous silicon layer) with embedded fullerene molecules C₆₀ was studied. The degradation of fullerene-containing layers as a result of irradiation with a strongly absorbed laser light was explored. It is shown that the layers with highest stability are obtained after high-temperature annealing in hydrogen. In this case, the photoluminescence spectra remain virtually unchanged when the layers are kept in air and irradiated with a high-intensity laser irradiation. Possible mechanisms of the phenomena studied are discussed.     

Effect of γ irradiation on the photoluminescence kinetics of porous silicon

The effect of γ irradiation on the photoluminescence decay dynamics in porous silicon is investigated. Growth of the photoluminescence intensity and decrease of the decay time in irradiated porous silicon are explained by a lowering of the barriers to recombination of spatially separated electrons and holes via tunneling. The γ irradiation of porous silicon leads to a greater dispersion of the decay time. Fiz. Tekh. Poluprovodn. 33, 1462–1464 (December 1999)     

Effect of low-temperature annealing on photoluminescence of silicon nanocluster structures

Experimental data on the photoluminescence spectra of Si nanocluster structures obtained after high-temperature annealing (1150°C) of SiO _x films deposited onto Si and subsequent low-temperature annealing of the films at the temperature 450°C in different ambient are reported. It is shown that the photoluminescence intensity substantially increases after low-temperature annealing and the most-pronounced effect is observed after annealing in the oxygen-nitrogen mixture. In this case, the photoluminescence spectrum is shifted to longer wavelengths and shaped as a broad band with a peak around 800 nm. The processes responsible for the increase in the PL intensity on low-temperature annealing in the oxygen-nitrogen mixture are defined by reconstruction of the Si/SiO₂ interfaces and by energy levels formed at the interfaces and involved in recombination of nonequilibrium charge carriers. The quasichemical reactions that bring about the formation of such levels involve oxygen and nitrogen atoms, and the centers, at which the reactions are initiated, are unsaturated valence bonds at the interfaces between Si nanoclusters and the SiO₂ matrix.     

Radiation damage in N+-implanted ZnSe

The radiation damage in 200 keV N⁺ -ion implanted (111) single crystalline ZnSe has been studied as a function of dosage and annealing treatment using cross-sectional transmission electron microscope techniques. For dosages less than 10¹⁴ /cm² no observable damage is present at room temperature or after annealing at 700°C for one hour. For a dosage 10¹⁵/cm² the radiation damage is observable at room temperature and on annealing the initial high density of small black dot defects form Frank loops which on growing still further form prismatic vacancy type loops. For dosages of 10¹⁷/cm² a very high concentration of defects form at room temperature although the material remains single crystalline. On annealing at 700°C dodecahedron voids form in the damage region and cause swelling of ? 1%. The stresses induced by this swelling is accommodated by dislocations of the a/2 <110> type which glide in from the surface on the {111} slip planes. The distribution of the radiation damage for all the dosages and on annealing up to 700°C is Gaussian with a peak coinciding with the projected range of N⁺ -ions in ZnSe as predicted by the Lindhard, Scharff and Schiot (LSS) theory. Auger depth profiling on 10¹⁷ N -ions/cm² implanted ZnSe revealed no nitrogen in the damage zone of either the as implanted (R.T.) ZnSe or those annealed at 700°C.     

Defect engineering in implantation technology of silicon light-emitting structures with dislocation-related luminescence

Results obtained in development of physical foundations of ion implantation technology for fabrication of silicon light-emitting structures (LESs) based on dislocation-related luminescence and intended for operation at wavelengths close to ∼1.6 μm are summarized. The development of the concept of defect engineering in the technology of semiconductor devices makes it possible to determine the fundamental aspects of the process of defect formation; reveal specific features of the emission spectra related to changes in the implantation conditions of Er, Dy, Ho, O, and Si ions and the subsequent annealing; and design light-emitting structures with a desirable spectrum of luminescent centers and extended structural defects. The technological conditions in which only a single type of extended structural defect (Frank loops, perfect prismatic loops, or pure edge dislocations) is introduced into the light-emitting layer are found, which enables analysis of the correlation between the concentration of extended defects of a certain type and the intensity of lines of the dislocation-related luminescence. The key role of intrinsic point lattice defects in the origination and transformation of extended structural defects and luminescent centers responsible for the dislocation-related luminescence is revealed. It is found that the efficiency of luminescence excitation from the so-called D1 centers, which are of particular interest for practical applications, varies by more than two orders of magnitude between structures fabricated using different technological procedures. High-efficiency silicon light-emitting diodes with room-temperature dislocation-related luminescence have been fabricated.     

Effect of implantation and annealing conditions on the photoluminescence emission of Si nanocrystals ion beam synthesised in SiO2

In this article, we present a systematic study of the evolution of photoluminescence (PL) emission of Si nanocrystals with elaboration conditions. Si nanocrystals synthesised in SiO₂ by ion implantation and annealing at 1100°C show a wide (0.3 eV) and a very intense PL emission centred at 1.5–1.7 eV, linked to the presence of the nanocrystals. The intensity of this emission shows a typical behaviour with the annealing time, with a fast transitory increase to reach an asymptotical saturation. There is a linear increase of the PL intensity at saturation with the dose. Two regimes are clearly observed for the evolution of the PL energy position as a function of the annealing time for different peak supersaturations (s): (i) for s<5%, there is a decrease transient followed by a saturation state of the maximum peak energy, and (ii) for s5% the PL energy presents an increase transient followed by a saturation state.     

Preparation of n+ emitter on p-type silicon wafer using the spin-on doping method

There is a strong need for cost reduction in manufacturing crystalline silicon solar cells, and one of the approaches is to merge two steps of silicon wafer processing into one step without degrading the performance of solar cells. In this work, we intended to employ the spin-on doping (SOD) method for the purpose of dual tasks, phosphorus diffusion to form n⁺ emitters and antireflection coating (ARC) to reduce optical reflection. Different from the commercial SOD solutions based on SiO₂, we used tetraethylorthosilicate (TEOS) to prepare SOD solutions containing different concentrations of phosphorus acid as the phosphorus doping source. We first investigated the dependence of the sheet resistance of the n⁺ emitters on the concentration of phosphorus acid in the SOD solution as well as the thermal diffusion temperature and time. It was found that all these three factors can effectively influence the sheet resistance of the n⁺ emitters, suggesting a relatively easier optimization process for forming n⁺ emitters using the SOD method. The SOD thin films formed after the thermal diffusion process were found to be SiO₂ films. We then investigated the antireflection properties of the as-grown SOD thin films, and found that they can effectively reduce the optical reflection of silicon wafers.     

Effect of thermal annealing and chemical treatment on the photoluminescence of porous silicon

Changes in the intensity of photoluminescence and in the IR absorption spectra of porous silicon samples are studied during chemical annealing and chemical treatment. It is found that processing porous silicon in HCl+Zn increases the photoluminescence intensity by more than a factor of 2 and affects the way the intensity is reduced by annealing. A comparison of the observed changes with IR spectra suggests that Si-H_x bonds play a key role in efficient photoluminescence in porous silicon. Fiz. Tekh. Poluprovodn. 32, 494–496 (April 1998)     

Low-temperature photoluminescence in holmium-doped silicon

In this paper the photoluminescence (PL) of holmium-doped silicon is discussed. The silicon was first implanted with holmium ions at energies of 1–2 MeV and doses of 1×10¹³–3×10¹⁴ cm⁻², and then annealed at temperatures of 620–900 °C for 0.5–1 h. In order to increase the concentration of electrically and optically active centers, the silicon was implanted a second time with oxygen ions at energies of 0.14–0.29 MeV and doses of 1×10¹⁴–3×10¹⁵ cm⁻². Several photoluminescence lines, which are attributable to the transitions of electrons from the first excited state of the Ho³⁺ ion (⁵ I ₇) to the ground state (⁵ I ₈), were observed. The amplitudes of the most intense lines, which correspond to transitions at frequencies 5119 and 5103 cm⁻¹, decreased by more than an order of magnitude in the temperature range 4.2−78 K. The PL intensity of the holmium ions increased with increasing concentrations of the implanted rare-earth ions and oxygen. Fiz. Tekh. Poluprovodn. 33, 420–422 (April 1999)     

Annealing of damage in Se+-implanted indium phosphide

The production and annealing of damage in (100) InP implanted with Se⁺ ions at 77 K, room temperature and 180°C have been studied by channeling and differential Hall measurements. For ion energies from 100 to 400 keV, fluences of 10¹⁴ and 10¹⁵ cm^?2 produce amorphous layers which extend to the surface in samples implanted at 77 K or room temperature, while the samples implanted at 180°C remain crystalline. According to the channeling measurements, amorphous layers less than 2000 Å thick produced by either 77 K or room-temperature implants are completely reordered by annealing at 750°C for 10 min, while the post-anneal residual disorder of thicker layers is linearly dependent on the initial amorphous layer thickness. After annealing, samples implanted at 180°C have higher sheet carrier concentrations and mobilities but considerably broader carrier concentrations than samples similarly implanted at either 77 K or room temperature, even when the amorphous layers in the latter samples are completely reordered. It is considered that for most applications heated implants should be used to avoid the formation of amorphous layers.     

Effect of doping profile on avalanche noise of silicon IMPATT diodes

The open-circuit spectral noise-voltage density e2/?f of silicon IMPATT diodes with different punchthrough factors has been measured. A noise reduction has been obtained for diodes with punchthrough factors > 1. This is in agreement with theoretical curves calculated on the basis of the noise theory of Gummel and Blue.