A study of Zn diffusion in InP at low temperature

The diffusion of Zn in InP at low temperature is investigated. The experiment is accomplished in an evacuated and sealed quartz ampoule using Zn_eP₂ as the source of Zn. The electrical characteristics of the diffusion samples obtained by the isotemperature process and the two-temperature process have been compared. It is found that with the two-temperature process one can obtain a smooth, damageless and high-concentration surface layer. This process has been applied to fabricate InGaAsP/InP light emitting diodes, and the diodes obtained have an output power of ≥1mW with a series resistance of 2–5Ω. The behaviors of Zn diffusion in InP are discussed.     

Study on the diffusion of Cd and Zn IN InP

 The study on the diffusion of Cd and Zn in InP at a temperature range of 450—700℃ and their compared results are described in this paper.The effects of various impurity sources,such as Cd and Zn as well as their compounds on the results of diffusion are investigated intensively.Using X_j~2/t ratio defined by the square of the diffusion depth X_j~2 and time t as a measure of the diffusion velocity,we show the plots of X_j~2/t vs temperature T.It is found that the diffusion velocity of Cd, especially CdP_2 diffusion sources is slower and thus easier to control the diffusion depth and concentration.However they are more ideal diffusion impurity sources.We explain the complication phenomena of Cd-and Zn-diffusion in InP with neutral complex presented by Tien(1979).     

LOW TEMPERATURE OPEN TUBE Zn DIFFUSION IN InP/InGaAs(P)

To fabricate quasi-planar optoelectronic integrated circuits(OEICs),a new open tube Zndiffusion method has been developed.The characteristics of Zn diffusion in InP/InGaAs(P)heterostrueturematerials at comparatively low temperature have been studied,and it has been found for the first time that Zndiffusion rate is proportional to the square of phosphorus content of the InGaAsP materials.     

Planar InP/InGaAs-APD with a guardring formed by Cd diffusion through SiO2

A graded junction, with a breakdown voltage twice as high as that for an abrupt junction, was formed in n-InP by Cd diffusion through SiO2 film. Planar-type InP/InGaAs-APDs with this graded junction for a guardring showed a uniform multiplication gain over the whole sensitive area with no local breakdown. Cd diffusion through SiO2 was revealed to be very useful for formation of the guardring.     

Open ampoule diffusion in InP

We describe a new diffusion process to obtain Zn-doped p+-InP layers in an open ampoule in a PH3/H2 atmosphere. Using this process, we are able to control the diffusion and to realise planar and abrupt junctions while conserving the mirror-like InP surface.     

杂质Zn在InP中的扩散机制

介绍了杂质Zn在InP中的两种扩散机制,间隙-替代机制和Kick-out机制.InP为n型时,扩散机制为间隙-替代式;InP为p型时,扩散机制为Kick-out式.重点介绍了三种不同模型,解释Zn在InP中通过间隙-替代机制进行扩散时,空穴浓度与Zn浓度不同的原因,并评价了三种模型.     

Zn doping of InP, InAsP/InP, and InAsP/InGaAs heterostructures through metalorganic vapor phase diffusion (MOVPD)

Zinc incorporation by post-growth metalorganic vapor phase diffusion (MOVPD) is used to achieve high p-doping, which is desirable for the fabrication of photodiodes. Diethylzinc (DEZ) is used as precursor and Zn is diffused into InP and InAs_0.6P epitaxial layers grown by low pressure metalorganic vapor phase epitaxy (MOVPE) on different substrate orientations, enabling the investigation of the dislocation density on the Zn incorporation. Diffusion depths are measured using cleave-and-stain techniques, resistivity measurements, electrochemical profiling, and secondary ion mass spectroscopy. High hole concentrations of, respectively, 1.7 10¹⁹ and 6 10¹⁸ cm⁻³, are obtained for, respectively, InAs_0.60P and InP. The diffusion coefficients are derived and the Zn diffusion is used for the fabrication of lattice-mismatched planar PIN InAsP/InGaAs photodiodes.     

Effects of S,Si, or Fe dopants on the diffusion of Zn in InP during MOCVD

Diffusion of Zn in InP during growth of InP epitaxial layers has been investigated in layer structures consisting of Zn-InP epilayers grown on S-InP and Fe-InP substrates, and on undoped InP epilayers. The layers were grown by metalorganic chemical vapour deposition (MOCVD) atT = 625° C andP = 75 Torr. Dopant diffusion profiles were measured by secondary ion mass spectrometry (SIMS). At sufficiently high Zn doping levels ([Zn] ≥8 × 10¹⁷ cm⁻³) diffusion into S-InP substrates took place, with accumulation of Zn in the substrate at a concentration similar to [S]. Diffusion into undoped InP epilayers produced a diffusion tail at low [Zn] levels, probably associated with interstitial Zn diffusion. For diffusion into Fe-InP, this low level diffusion produced a region of constant Zn concentration at [Zn] ≈ 3 × 10¹⁶ cm⁻³, due to kick-out of the original Fe species from substitutional sites. We also investigated diffusion out of (Zn, Si) codoped InP epilayers grown on Fe-InP substates. The SIMS profiles were characterised by a sharp decrease in [Zn] at the epilayer-substrate interface; the magnitude of this decrease corresponded to that of the Si donor level in the epilayer. For [Si] ≫ [Zn] in the epilayer no Zn diffusion was observed; Hall measurements indicated that the donor and acceptor species in those samples were electrically active. All these results are consistent with the presence of donor-acceptor interactions in InP, resulting in the formation of ionised donor-acceptor pairs which are immobile, and do not contribute to the diffusion process.     

InP/In_xGa_(1-x)As异质结构中Zn元素的扩散机制

采用闭管扩散方式实现了Zn元素在晶格匹配InP/In_(0.53)Ga_(0.47)As及晶格失配InP/In_(0.82)Ga_(0.18)AS两种异质结构材料中的P型掺杂,利用二次离子质谱(SIMS)以及扫描电容显微技术(SCM)对Zn在两种材料中的扩散机制进行了研究.SIMS测试表明:Zn元素在晶格失配材料中的扩散速度远大于在晶格匹配材料中的扩散速度,而SCM测试表明:两种材料中的实际PN结深度与SIMS测得的Zn扩散深度之间存在一定的差值,这是由于扩散进入材料中的Zn元素并没有被完全激活,而晶格失配材料中Zn的激活效率相对更低,使得晶格失配材料中Zn元素扩散深度与PN结深度的差值更大.SCM法是一种新颖快捷的半导体结深测试法,对于半导体器件工艺研究具有重要的指导意义.     

The lattice position of diffused Zn in InP

We have measured the substitutional fraction (f_s) for Zn atoms diffused into InP crystals using the proton-induced x-ray excitation (PIXE) technique. Diffusion times ranged from 15–60 min at 425–650° C. For several samples with diffusion depths in the range 0.75-3.7 μm (as determined by SIMS analysis), we find that the Zn impurity atoms reside almost totally on lattice sites: f_s = 0.9 ± 0.1. Contrary to results of an earlier study, we find no evidence for precipitates in the diffused layers. However, only ∼10^-3-10^-1 of the Zn is electrically active, consistent with Tuck and Hooper’s suggestion of neutral V_p Zn_In V_p complexes.     

Planar InP avalanche photodiode with Zn-diffused guard ring

A guard ring structure with a p+-n?-n junction formed by Zn diffusion at 450°C gave a high gain planar InP avalanche photodiode. A maximum multiplication factor of more than 50 was obtained uniformly within the photosensitive area without edge breakdown.     

Out-diffusion and reactivation of Zn in InP substrates

The influence of temperature on p-doping in Zn-diffused InP substrates has been investigated. By cooling the diffused InP samples very slowly after diffusion or subjecting them to heat treatment, significant out-diffusion of Zn has been observed. By heat-treating with rapid cooling, a substantial fraction of the incorporated but electrically inactive Zn atoms can be reactivated, resulting in a drastically increased acceptor concentration.     

Planar fully ion implanted InP power junction FET's

This letter reports on the fabrication and performance of planar all ion-implanted 1.0-µm gate length InP power junction field effect transistors (JFET's). The devices were fabricated utilizing n+ implantation, a AuZn/TiW/Au gate metallization, and an n+ drain ledge. At 4.5 GHz, the 300-µm gate width JFET's exhibited maximum insertion gains of up to 13 dB and scaled output powers as high as 1 W/mm with 3-dB gain.     

LPE制作平面型InGaAs/InP APD

叙述了用液相外延(LPE)制作 InGaAsP/InP 雪崩光电二极管(APD)的物理性能。分析了该器件的设计参数。介绍了器件结构、器件制作中 LPE 生长条件及器件性能。最后,评述了器件发展水平及改进意见。     

Planar InP/InGaAsP three-dimensional graded-junction avalanche photodiode

A new planar InP/InGaAsP avalanche photodiode, which is fabricated by Be⁺implantation through a dish-shaped InGaAs mask, has been developed. A three-dimensional graded junction is obtained and a uniform gain as high as 30 achieved without edge or surface breakdown. The dish-shaped InGaAs implantation mask is formed by a photoelectrochemical etching technique. Device modeling indicates that the graded junction and low doping concentration can prevent edge breakdown and greatly suppress the surface field. The diode has a separated absorption and multiplication structure grown by hydride vapor-phase epitaxy. These devices exhibit low primary dark currents (≈ 1 nA), and high quantum efficiencies close to that of an InGaAs p-i-n at 1.3-µm wavelength. Sensitivity measurements at bit rates of 1.7 Gbit/s give a minimum average receiver power required for 10^-9BER of -35.5 dBm.     

InGaAs/InP材料的Zn扩散技术

使用MOCVD反应室进行了InGaAs和InP材料上的Zn扩散工艺条件研究.通过控制扩散温度、扩散源浓度和扩散时间三个主要工艺参数,研究了InGaAs/InP材料的扩散系数和扩散规律,获得了优化的扩散条件.试验表明,该扩散工艺符合原子扩散规律,扩散现象可以用填隙-替位模型解释.样品经过快速退火过程,获得了极高的空穴浓度.InP的空穴浓度达到7.7×1018/cm3,而InGaAs材料达到7×1019/cm3.在优化的扩散条件下,Zn扩散的深度和浓度精确可控,材料的均匀性好,工艺重复性好,能够应用于光电探测器或其他器件.     

平面型InP/InGaAs雪崩光电二极管多级台阶结构研究

平面型雪崩光电二极管(APD)在结弯曲处具有更高的电场,易导致结边缘的提前击穿.运用FEMLAB软件对多级台阶结构的平面型InP/lnGaAs APD的电场分布进行了二维有限元模拟,在表面电荷密度为5×10~(11)cm~(-2)时分析了台阶级数、台阶高度等因素对边缘提前击穿特性的抑制程度.通过理论研究对平面InP/InGaAS APD进行了优化.

Abstract：

For planar-type avalanche photodiode (APD), it is hard to suppress edge pre-breakdown with double-stepped p-region profile. In order to suppress the edge pre-breakdown, amulti-stepped p-region is proposed and studied. A finite element two-dimensional (2-D) simulation is performed to study the electric field of planar-type APD with multi-stepped p-region. The effects of the step number and deep in suppressing the edge pre-breakdown are analyzed and the planar-type APD structure is optimized theoretically.     

STUDY ON Zn DIFFUSION IN Ge

In this report the diffusion of Zn into Ge is investigated.The experiments are accomplishedin an evacuated and sealed quartz ampoule using Zn as the diffusion source.The relation of the X_j-t and C_s-(1/T)is given.The influence of the source temperature on the surface micrograph is investigated.It is foundthat using the two-temperature process a smooth surface layer can be obtained.The effect of the thickness ofthe SiO_2 films on the mask ability for Zn is given.The leakage current can be reduced by evacuation annealing,     

Be diffusion in InGaAs/InP heterojunction bipolar transistors

Classic signatures of Be diffusion were observed in InAlAs/InGaAs HBT's after elevated temperature bias stress, i.e., a positive shift in the Gummel plot, higher collector ideality, and higher offset voltage. An activation energy of 1.57 eV was calculated. Lifetimes of 3.3×106 h and 37000 h were extrapolated for low and high power operation, respectively. In contrast, an InP/InGaAs HBT with a C doped base showed no signatures of C diffusion. The results show that Be diffusion is manageable at lower power. They also support the idea that C is more stable than Be in this material system     

InP基光电探测器材料的MOCVD锌扩散

锌(Zn)扩散是制作InP基光电探测器(PD)的重要工艺过程.分析了锌扩散的机制,利用金属有机化学气相沉积(MOCVD)设备对InP基PD及雪崩光电探测器(APD)材料进行了锌扩散,由于MOCVD设备具有精确的温度控制系统,所以该扩散工艺具有简单、均匀性好、重复性好的优点.对于扩散后的样品,采用电化学C-V方法和扫描电子显微镜(SEM)等测试分析手段,研究了退火、扩散温度、扩散源体积流量和反应室压力等主要工艺参数对InP材料扩散速率和载流子浓度的影响,并将该锌扩散工艺应用于InP基光电探测器和雪崩光电探测器的器件制作中,得到了优异的器件性能结果.