Investigation of the 1.20-eV photoluminescence band in rapid thermal annealed InP

Deep level photoluminescence of rapid thermal annealed (RTA) undoped liquid-encapsulated Czochralski InP has been studied. Aband occurring at 1.20 eV, not observed in as-grown sample, became a dominant deep level peak after a 10-s rapid thermal annealing process. However, after high temperature or prolonged annealing, it disappeared again. Ion implantation by various species such as phosphorus, argon, and tin was carried out. The 1.20-eV band observed after RTA was found to be suppressed by the phosphorus-implantation but enhanced by tin implantation, suggesting that its origin may be due to the formation of phosphorus vacancy single point defect.     

Rapid thermal annealing of dual Si and P implants in InP

In this study we evaluate the effects of dual implantation with different doses of Si and P on dopant activation efficiency and carrier mobility in InP:Fe. The implants were activated by a rapid thermal annealing step carried out in an optimized phosphoruscontaining ambient. For high dose implants (10¹⁴–10¹⁵ cm⁻²), which are typically employed for source/drain regions in FETs, dual implantation of equal doses of Si and P results in a higher sheet carrier concentration and lower sheet resistance. For 10¹⁴ cm⁻² Si implants at 150 keV, the optimal P co-implant dose is equal to the Si dose for most anneal temperatures. We obtain an activation efficiency of ∼70% for dual implanted samples annealed at 850° C for 10 sec. The high activation efficiencies and low sheet resistances obtained in this study emphasize the importance of stoichiometry control through the use of P co-implants and a phosphorus-containing ambient during the thermal processing of InP.     

Beryllium Ion Implantation into GaAs and Pseudomorphic AIGaAs/lnGaAs/GaAs Heterostructure

Implantations of Be, Be + P, Be + F, Be + P +F, BeF and Mg + P into GaAs and AlGaAs/InGaAs/GaAs pseudomorphic heterostructure were evaluated by secondary ion mass spectrometry profilings and electrical resistivity measurements. Rapid thermal annealing causes a strong diffusion of Be when implanted alone. Co-implantation with P prevents both diffusion and degradation of the Gaussian-shape implant distribution and thus improves the semiconductor sheet resistivity. Annealing at 850°C for 10 s for a Be + P co-implant results in a 60% activation efficiency, and lower diffusion and resistivity when compared to single Be, Be + F, Be + F + P, BeF, and Mg + P implanted at the same dose.     

Si-and Be-implantations in lnP:Fe activated by halogen lamp rapid thermal annealing

Halogen lamp rapid thermal annealing is performed at different temperatures and time durations to activate InP:Fe implanted with 200 keV Si and 60 keV Be ions in the range of 5 x 10¹² -4 x 10¹⁴ cm^-2 . Better electrical properties are obtained in the rapid thermal annealed material than in conventional furnace annealed material. The mea-sured maximum dopant activation and electron mobility for a 200 keV/1 x 10¹⁴ cm^-2 Si-implant are 76% and 1440 cm²/V-s, respectively. For a 60 keV/4 x 10¹⁴ cm^-2 Be-implant an activation of 28% and a sheet resistance of 810 Ω/sq are obtained by using rapid thermal annealing. An implant profile broadening is observed in Be-implanted samples activated with either furnace annealing or rapid thermal annealing.     

Halogen lamp rapid thermal annealing of Si- and Be-implanted In0.53Ga0.47As

Halogen lamp rapid thermal annealing was used to activate 100 keV Si and 50 keV Be implants in In_0.53Ga_0.47As for doses ranging between 5 × 10¹²−4 × 10¹⁴ cm⁻². Anneals were performed at different temperatures and time durations. Close to one hundred percent activation was obtained for the 4.1 × 10¹³ cm⁻² Si-implant, using an 850° C/5 s anneal. Si in-diffusion was not observed for the rapid thermal annealing temperatures and times used in this study. For the 5 × 10¹³ cm⁻² Be-implant, a maximum activation of 56% was measured. Be-implant depth profiles matched closely with gaussian profiles predicted by LSS theory for the 800° C/5 s anneals. Peak carrier concentrations of 1.7 × 10¹⁹ and 4 × 10¹⁸ cm⁻³ were achieved for the 4 × 10¹⁴ cm⁻² Si and Be implants, respectively. For comparison, furnace anneals were also performed for all doses.     

Multi-step rapid thermal annealing of boron and indium implanted Hg1−xCdxTe

In this work, we are reporting the use of a two-step rapid thermal annealing (RTA) process (250°C, 100s+340°C, 30s) for the annealing of Hg_1−xCd_xTe (MCT) implanted layers over p-type (x=0.22) substrates. We report a high value of electrical activation (70%) of the indium implants after this short RTA treatment in inert Ar atmosphere. The need of two RTA steps in the annealing recipe is shown, and so the role played by each of them: the first step annihilates the implantation damage, while the second one produces the impurity electrical activation. However, for the boron case, no electrical activity was found after several annealing processes, behaving as an inert species for the case of this bulk MCT material. We also point out the change on the substrate electrical characteristics induced by the thermal treatments, and report the convenience of a subsequent low temperature furnace annealing (200°C, 72 h) to reduce back the bulk carrier concentration to values low enough to achieve an n⁺-p IR detector structure.     

Ar气氛下快速退火对CZ-Si单晶中FPD的影响

将Si片经Secco腐蚀液腐蚀,用光学显微镜和原子力显微镜(AFM)对CZ-Si单晶中的流动图形缺陷(FPD)的形貌、分布及结构进行了研究,对Si片进行了湿氧化处理并采用较新的快速退火方法(RTA),在Ar气氛下对Si片进行热处理,研究了退火温度和退火时间对FPD缺陷密度的影响.结果表明,FPDs缺陷在1 100 ℃以下非常稳定;但是在1 100 ℃以上的温度,尤其在1 200℃对Si片进行RTA处理后,Si片中FPD的密度大大降低,而且随着的退火时间的延长,密度不断下降.     

Pd-Ge contact to n-GaAs with the TiW diffusion barrier

Pd-Ge based ohmic contact to n-GaAs with a TiW diffusion barrier was investigated. Electrical analysis as well as Auger electron spectroscopy and the scanning electron microscopy were used to study the contact after it was subjected to different furnace and rapid thermal annealing and different aging steps. All analyses show that TiW can act as a good barrier metal for the Au/Ge/Pd/n-GaAs contact system. A value of 1.45 × 10⁻⁶ Ω-cm² for the specific contact resistance was obtained for the Au/TiW/Ge/Pd/n-GaAs contact after it was rapid thermally annealed at 425°C for 90 s. It can withstand a thermal aging at 350°C for 40 h with its ρ_c increasing to 2.94 × 10⁻⁶Ω-cm² and for an aging at 410°C for 40 h with its ρ_c increasing to 1.38 × 10⁻⁵ Ω-cm².     

Current transport in fluorine implanted GaAs

Effects of fluorine implantation in GaAs have been investigated by electrical characterization. Ion implantation at 100 keV energy was conducted with doses of 10¹¹ and 10¹²/cm². The effect of fluorine implantation on current-voltage (I-V) characteristics of Schottky diodes was significant. Carrier compensation was observed after implantation by the improved I-V characteristics. The lower dose implanted samples showed thermionic emission dominated characteristics in the measurement temperature range of 300 to 100K. The starting wafer and the low dose implanted samples after rapid thermal annealing (RTA) showed similar I-V properties with excess current in the lower temperature range dominated by recombination. The higher dose implanted samples showed increased excess current in the whole temperature range which may result from the severe damage-induced surface recombination. These samples after RTA treatment did not recover from implantation damage as in the low dose implantation case. However, very good I-V characteristics were seen in the higher dose implanted samples after RTA. The influence of the higher dose ion implantation was to produce more thermal stability. The results show the potential application of fluorine implantation in GaAs device fabrication.     

Sensitivity analysis of ion implanted silicon wafers after rapid thermal annealing

In this study, we have investigated sensitivities of the ion implanted silicon wafers processed by rapid thermal annealing (RTA), which can reveal the variation of sheet resistance as a function of annealing temperature as well as implantation parameters. All the wafers were sequentially implanted by the arsenic or phosphorous implantations at 40, 80, and 100 keV with the dose level of 10¹⁴ to 2 × 10¹⁶ ions/cm². Rapid thermal annealing was carried out for 10 s by the infrared irradiation at a temperature between 850 and 1150°C in the nitrogen ambient. The activated wafer was characterized by the measurements of the sheet resistance and its uniformity mapping. The values of sensitivities are determined from the curve fitting of the experimental data to the fitting equation of correlation between the sheet resistance and process variables. From the sensitivity values and the deviation of sheet resistance, the optimum process conditions minimizing the effects of straggle in process parameters are obtained. As a result, a strong dependence of the sensitivity on the process variables, especially annealing temperatures and dose levels is also found. From the sensitivity analysis of the 10 s RTA process, the optimum values for the implant dose and annealing temperature are found to be in the range of 10¹⁶ ions/cm² and 1050-1100°C, respectively. The sensitivity analysis of sheet resistance will provide valuable data for accurate activation process, offering a guideline for dose monitoring and calibration of ion implantation process.     

Optical and microstructural characterization of the effects of rapid thermal annealing of CdTe thin films grown on Si (100) substrates

The effects of rapid thermal annealing (RTA) on CdTe/Si (100) heterostructures have been studied in order to improve the structural quality of CdTe epilayers. Samples of CdTe (111) polycrystalline thin films grown by vapor phase epitaxy (VPE) on Si (100) substrates have been investigated. The strained structures were rapidly thermally annealed at 400°C, 450°C, 500°C, 550°C, and 600°C for 10 sec. The microstructural properties of the CdTe films were characterized by carrying out scanning electron microscopy (SEM), x-ray diffraction (XRD), and atomic force microscopy (AFM). We have shown that the structural quality of the CdTe epilayers improves significantly with increasing annealing temperature. The optimum annealing temperature resulting in the highest film quality has been found to be 500°C. Additionally, we have shown that the surface nucleation characterized by the island size distribution can be correlated with the crystalline quality of the film.     

Ion implantation and rapid thermal processing of Ill-V nitrides

Ion implantation doping and isolation coupled with rapid thermal annealing has played a critical role in the realization of high performance photonic and electronic devices in all mature semiconductor material systems. This is also expected to be the case for the binary III-V nitrides (InN, GaN, and A1N) and their alloys as the epitaxial material quality improves and more advanced device structures are fabricated. In this article, we review the recent developments in implant doping and isolation along with rapid thermal annealing of GaN and the In-containing ternary alloys InGaN and InAlN. In particular, the successful n- and p-type doping of GaN by ion implantation of Si and Mg+P, respectively, and subsequent high temperature rapid thermal anneals in excess of 1000°C is reviewed. In the area of implant isolation, N-implantation has been shown to compensate both n- and p-type GaN, N-, and O-implantation effectively compensates InAlN, and InGaN shows limited compensation with either N- or F-implantation. The effects of rapid thermal annealing on unimplanted material are also presented.     

Electrical and optical characterization studies of lower dose Si-implanted AlxGa1−xN

Electrical and optical activation studies of lower dose Si-implanted Al_xGa_1?xN (x=0.14 and 0.24) have been made systematically as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1×10¹³ cm^?2 to 1×10¹⁴ cm^?2 at room temperature. The samples were proximity cap annealed from 1,100°C to 1,350°C with a 500-Å-thick AlN cap in a nitrogen environment. Nearly 100% electrical activation efficiency was obtained for Al_0.24Ga_0.76N implanted with a dose of 1 × 10¹⁴ cm^?2 after annealing at an optimum temperature around 1,300°C, whereas for lower dose (≤5×10¹³ cm^?2) implanted Al_0.24Ga_0.76N samples, the electrical activation efficiencies continue to increase with anneal temperature up through 1,350°C. Seventy-six percent electrical activation efficiency was obtained for Al_0.14Ga_0.86N implanted with a dose of 1 × 10¹⁴ cm^?2 at an optimum anneal temperature of around 1,250°C. The highest mobilities obtained were 89 cm²/Vs and 76 cm²/Vs for the Al_0.14Ga_0.86N and Al_0.24Ga_0.76N, respectively. Consistent with the electrical results, the photoluminescence (PL) intensity of the donor-bound exciton peak increases as the anneal temperature increases from 1,100°C to 1,250°C, indicating an increased implantation damage recovery with anneal temperature.     

Improvement of GaAs/AlGaAs quantum well laser diodes by rapid thermal annealing

Post-growth annealing is shown to improve the laser diode quality of GaAs/AlGaAs graded-index separate confinement heterostructure quantum well laser diode structures grown at a nonoptimal substrate temperature lower than 680°C by molecular beam epitaxy. Reduction by a factor of up to three in the threshold current was accompanied by a reduction in the interface trap density. The reduced threshold current is still higher than that of laser diodes grown at the optimal temperatures which are between 680 and 695°C. The improvement in laser diode performance is ascribed to the reduction of interface nonradiative recombination centers.     

Co,Fe, and Ti Implants in InGaAs and Co Implants in InP at 200° C

Elevated temperature (200° C) single- and multiple-energy Co implants inn-type InP, Co and Fe implants in n-type In_0.53Ga_0.47As, and Ti implants inp-type In_0.53Ga_0.47As were performed. For elevated temperature, single-energy Co and Fe implants, no satellite peaks at various locations like 0.8R _P, R_P + ΔR_P, and 2R _P R _P is the projected range and ΔR _P the straggle of the implant) are observed, in contrast to the case of room temperature implants. However, the outdiffusion of the implant is as severe as that in room temperature implantation for high temperature anneals. Indiffusion of the implant also occurs, but it is not as severe as the outdiffusion. High temperature annealing of Ti-implanted material results in a slight indiffusion of Ti, with minimal redistribution or outdiffusion. For all elevated temperature implants, the lattice quality of the annealed material is close to that of the virgin unimplanted material. For all ion species used in this study, resistivities close to the intrinsic limit are obtained in the implanted and annealed materials.     

Optimization of RTA parameters to produce ultra-shallow, highly activated B+, BF 2 + , and As+ ion implanted junctions

The effects of time, temperature, ramp-up, and ramp-down rates with rapid thermal annealing employing a STEAG AST SHS3000 were investigated on 1.0 and 2.0 keV ¹¹B⁺, 2.2, 5.0, and 8.9 keV ⁴⁹BF ₂ ⁺ , and 2 KeV ⁷⁵As⁺, 1E15/cm² samples implanted in a Varian VIISion-80 PLUS ion implanter at 0^o tilt angles. These annealed samples were analyzed by four-point probe, secondary ion mass spectrometry (SIMS), and in select cases by spreading resistance profiling (SRP) and transmission electron microscopy (TEM). To ensure reproducibility and to minimize oxidation enhanced diffusion as an uncontrolled variable, the O₂ background concentration in N₂ was maintained at a controlled low level. Under these conditions, ramp-rates alone were found not to be significant. Spike anneals (1050°C, ～ 0 s) with fast ramp-rates (240°C/s) and fast cool down rates (86°C/s) provided the shallowest junctions, while still yielding good sheet resistance values. Post annealed samples were examined for extended defect levels (by TEM) and trapped interstitial concentrations. Fluorine concentration measurements were employed to qualitatively explain differences in the B diffusion from ¹¹B⁺ and ⁴⁹BF ₂ ⁺ ion implants at various energies. The 2.2 keV ⁴⁹BF ₂ ⁺ “fast” spike annealed sample at 1050°C exhibited limited, if any, enhanced diffusion, yielding a SIMS junction depth of 490Å, an electrical junction of 386Å (by SRP) and a sheet resistance of 406 ohm/sq.     

Structural and optical characterization of InP/GalnP islands grown by solid-source MBE

We report on the growth of InP/GalnP islands on GaAs substrates by solidsource molecular beam epitaxy. It is shown by reflection high energy electron diffraction and atomic force microscopy that a rapid change from a twodimensional to a three-dimensional growth mode occurs at about nominally 1.5 monolayers (MLs) InP. Transmission electron microscopy measurements demonstrate the coherent incorporation of InP islands in an GalnP matrix for nominally 2.5 MLs InP. The energy of the InP photoluminescence (PL) shifts to lower energies (100 meV) when the growth interruption time between the island and cap layer growth is increased from 1 to 300 s in case of nominally 3 MLs InP. Simultaneously, an increase of the PL linewidth is observed from 30 to 60 meV. Room temperature photoreflectance measurements on samples with various InP thickness have been performed. Compared to PL measurements, an additional feature in the photoreflectance spectra is observed for samples with more than 7 MLs InP, which is attributed to a transition between excited electron and hole states of the islands.     

快速热退火前后ZnO及ZnO/Al薄膜性质的研究

鉴于直流反应溅射制ZAO膜对反应条件敏感,研究发现,经快速热退火(RTA)处理能放宽对反应条件的要求。实验中ZnO及ZnO/Al薄膜用直流反应磁控溅射法制备。选用金属Zn及金属合金Zn/Al靶。经快速热退火(RTA)后,通过XRD,UV-VIS-NIR分光光度计、四探针测方电阻等,研究了经不同温度RTA后ZnO及ZnO/Al薄膜的结晶状况、方电阻、电阻率、可见光透过率等的变化。对传统热退火和RTA进行了比较:经RTA600℃后电阻率减小5~9个数量级,达1×10–3·cm。     

The role of complementary species in P/Be and Ar/Be Co-implanted InP

Chemical and damage effects are used to explain the influence of complementary species on the activation of co-implanted InP. Recently Raoet al. have shown that the damage is the effective mechanism of enhancing activation efficiency and preventing in-diffusion in the P/Be and Ar/Be co-implanted InP. We have confirmed the results and further examined the role of the complementary species by varying their doses. Activation efficiencies as high as 75% and 69.5% were observed in the P/Be and Ar/Be co-implantation, respectively, which can be compared with 31.7% activation in the Be single implantation. Both activation efficiency and in-diffusion decreased as doses of P and Ar increased, that is, as the amount of damage increased. P/Be had always higher activation efficiency than that of Ar/Be when the doses of co-implants are equal. The ratio of the difference in the two activation efficiencies to that of P/Be was the largest at 10¹⁴ cm⁻² of co-implant dose. This behavior was attributed to the chemical effect of the co-implanted P. Photoluminescence results near the band edge showed that the intensity of the main peaks of Be single implantation decreased with increasing P and Ar doses.     

Electrical and optical activation studies of Si-implanted GaN

Comprehensive and systematic electrical and optical activation studies of Si-implanted GaN were made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1×10¹³ cm^?2 to 5×10¹⁵ cm^?2 at room temperature. The samples were proximity-cap annealed from 1050°C to 1350°C with a 500-Å-thick AlN cap in a nitrogen environment. The optimum anneal temperature for high dose implanted samples is approximately 1350°C, exhibiting nearly 100% electrical activation efficiency. For low dose (≤5×10¹⁴ cm^?2) samples, the electrical activation efficiencies continue to increase with an anneal temperature through 1350°C. Consistent with the electrical results, the photoluminescence (PL) measurements show excellent implantation damage recovery after annealing the samples at 1350°C for 20 sec, exhibiting a sharp neutral-donor-bound exciton peak along with a sharp donor-acceptor pair peak. The mobilities increase with anneal temperature, and the highest mobility obtained is 250 cm²/Vs. The results also indicate that the AlN cap protected the implanted GaN layer during high-temperature annealing without creating significant anneal-induced damage.