高温退火非掺杂磷化铟制备半绝缘材料

对液封直拉(LEC)非掺磷化铟(InP)进行930℃ 80h的退火可重复制备直径为50和75mm的半绝缘 (SI)衬底.退火是在密封的石英管内纯磷(PP)或磷化铁(IP)两种气氛下进行的.测试结果表明IP-SI InP衬底具有很好的电学性质和均匀性,而PP-SI的均匀性和电学参数都很差.在IP-SI样品的PL谱中出现与深缺陷有关的荧光峰.光激电流谱的测量结果表明:在IP气氛下退火获得的半绝缘磷化铟中的缺陷明显比PP-SI磷化铟的要少.并对退火后磷化铟中形成缺陷的机理进行了探讨.     

非掺半绝缘磷化铟晶片的制备及其均匀性

对高温退火非掺磷化铟(InP)制备的半绝缘晶片的电学性质和均匀性进行了研究.非掺低阻N型磷化铟晶片分别在纯磷气氛和磷化铁气氛下进行930℃、80h退火均可获得半绝缘材料.但在这两种条件下制备的两种50mm半绝缘晶片却呈现出不同的电学性质和均匀性.纯磷气氛下制备的磷化铟片的电阻率和迁移率分别达到106Ω·cm和1800cm2/(V·s);而在磷化铁气氛下退火获得的半绝缘片的电阻率和迁移率分别高达107Ω*cm和3000cm2/(V*s)以上.对这两种半绝缘片和原生掺铁磷化铟半绝缘片的PL-Mapping结果进一步比较表明:在磷化铁气氛下退火获得的半绝缘材料的均匀性最好,而在纯磷气氛下制备的半绝缘磷化铟的均匀性较差.     

非掺半绝缘磷化铟晶片的制备及其均匀性

对高温退火非掺磷化铟(InP)制备的半绝缘晶片的电学性质和均匀性进行了研究.非掺低阻N型磷化铟晶片分别在纯磷气氛和磷化铁气氛下进行930℃、80h退火均可获得半绝缘材料.但在这两种条件下制备的两种50mm半绝缘晶片却呈现出不同的电学性质和均匀性.纯磷气氛下制备的磷化铟片的电阻率和迁移率分别达到106Ω·cm和1800cm2/(V·s);而在磷化铁气氛下退火获得的半绝缘片的电阻率和迁移率分别高达107Ω*cm和3000cm2/(V*s)以上.对这两种半绝缘片和原生掺铁磷化铟半绝缘片的PL-Mapping结果进一步比较表明:在磷化铁气氛下退火获得的半绝缘材料的均匀性最好,而在纯磷气氛下制备的半绝缘磷化铟的均匀性较差.     

非掺半绝缘磷化铟晶片的制备及其均匀性

对高温退火非掺磷化铟 (In P)制备的半绝缘晶片的电学性质和均匀性进行了研究 .非掺低阻 N型磷化铟晶片分别在纯磷气氛和磷化铁气氛下进行 930℃、80 h退火均可获得半绝缘材料 .但在这两种条件下制备的两种 5 0 mm半绝缘晶片却呈现出不同的电学性质和均匀性 .纯磷气氛下制备的磷化铟片的电阻率和迁移率分别达到 10 6 Ω·cm和 180 0 cm2 / (V· s) ;而在磷化铁气氛下退火获得的半绝缘片的电阻率和迁移率分别高达 10 7Ω· cm 和30 0 0 cm2 / (V· s)以上 .对这两种半绝缘片和原生掺铁磷化铟半绝缘片的 PL - Mapping结果进一步比较表明 :在磷化铁气氛下     

空位和填隙缺陷对半绝缘InP单晶性质的影响

利用电学测试、正电子寿命谱和X射线衍射技术研究了原生和退火处理后InP单晶的空位和填隙缺陷.在原生掺铁半绝缘InP单晶中含有空位缺陷,这些空位产生深能级电学补偿缺陷,降低材料的电学性能.经高温磷化铁气氛下退火处理非掺InP制备的半绝缘材料,空位被充分抑制,却含有一定浓度填隙缺陷.根据实验结果分析了填隙和空位缺陷对掺铁半绝缘InP单晶材料电学性质和热稳定性的影响.     

空位和填隙缺陷对半绝缘InP单晶性质的影响

利用电学测试、正电子寿命谱和X射线衍射技术研究了原生和退火处理后InP单晶的空位和填隙缺陷.在原生掺铁半绝缘InP单晶中含有空位缺陷,这些空位产生深能级电学补偿缺陷,降低材料的电学性能.经高温磷化铁气氛下退火处理非掺InP制备的半绝缘材料,空位被充分抑制,却含有一定浓度填隙缺陷.根据实验结果分析了填隙和空位缺陷对掺铁半绝缘InP单晶材料电学性质和热稳定性的影响.     

InP中的深能级杂质与缺陷

综述了近年来关于InP中深能级缺陷和杂质的研究工作。讨论了深能级杂质及缺陷对InP材料性能的重要影响;介绍了深能级瞬态谱(DLTS)、光致发光谱(PL)、热激电流谱(TSC)、正电子寿命谱(PAS)、正电子深能级瞬态谱(PDLTS)等几种研究深中心的方法在研究InP时的某些特点;综合深能级缺陷和电学性质的测试结果,证明了半绝缘InP单晶材料的电学性能、热稳定性、均匀性等与材料中一些深能级缺陷的含量密切相关;分析了对掺铁和非掺退火两种半绝缘InP材料中深能级缺陷对电学补偿的影响;评述了对InP中的一些深中心所取得的研究成果和半绝缘InP的形成机理。     

高温退火处理提高半绝缘VGF-GaAs单晶的电学性能

垂直梯度凝固法(VGF)生长的低位错半绝缘(SI)GaAs单晶存在电阻率和迁移率低、电学补偿度小、均匀性差等问题.在3种不同温度条件下,对VGF-SI-GaAs晶片进行了加As压的闭管退火处理.结果表明,经过1160℃/12h的高温退火处理后,VGF-SI-GaAs单晶的电阻率、迁移率和均匀性均得到了显著提高.利用Hall、热激电流谱(TSC)、红外吸收法分别测试分析了原生和退火VGF-SI-GaAs单晶样品的电学性质、深能级缺陷、EL2浓度和C浓度,并与常规液封直拉法(LEC)SI-GaAs单晶样品进行了比较.原生VGF-SI-GaAs单晶巾的EL2浓度明显低于LEC-SI-GaAs单晶,经过退火处理后其EL2浓度显著增加,电学补偿增强,而且能级较浅的一些缺陷的浓度降低,因而有效提高了其电学性能.     

非掺及掺铁磷化铟中的残留施主缺陷

用辉光放电质谱(GDMS)测量了原生液封直拉(LEC)磷化铟(InP)的杂质含量.利用霍尔效应测到的非掺LEC-InP的自由电子浓度明显高于净施主杂质的浓度.在非掺和掺铁InP中都可以用红外吸收谱测到浓度很高的一个氢-铟空位复合体施主缺陷.这个施主的浓度随着电离的铁受主Fe2+浓度的增加而增加.这些结果表明半绝缘体中氢-铟空位复合体施主缺陷的存在对铁掺杂浓度和电学补偿都有重要影响.     

非掺及掺铁磷化铟中的残留施主缺陷

用辉光放电质谱(GDMS)测量了原生液封直拉(LEC)磷化铟(InP)的杂质含量.利用霍尔效应测到的非掺LEC-InP的自由电子浓度明显高于净施主杂质的浓度.在非掺和掺铁InP中都可以用红外吸收谱测到浓度很高的一个氢-铟空位复合体施主缺陷.这个施主的浓度随着电离的铁受主Fe2+浓度的增加而增加.这些结果表明半绝缘体中氢-铟空位复合体施主缺陷的存在对铁掺杂浓度和电学补偿都有重要影响.     

Fabrication of undoped semi-insulating InP by multiple-step wafer annealing

Recently, it was found that undoped semi-insulating InP can be reproducibly obtained by wafer annealing at 950°C for 40 h under phosphorus vapor pressure of 1 atm. Resistivity variation across the 50 mm diameter wafer after this annealing process, however, was in the range of 22.5–53.7%. In order to realize the fabrication of undoped semi-insulating (SI) InP with uniform electrical properties, multiple-step wafer annealing (MWA) procedure has been applied for the first time. It was found that two-step wafer annealing at 950°C for 40 h under phosphorus vapor pressure of 1 atm and at 807°C for 40 h under phosphorus vapor pressure ranging from 30 to 50 atm, was effective in improvement of the uniformity of the electrical properties of undoped SI InP. By the present MWA, the resistivity variation of 8–12% and the mobility variation of 2–4% could be obtained for 50 mm diameter wafers.     

半绝缘InP的铁掺杂激活与电学补偿

比较了掺Fe和非掺退火半绝缘(SI)InP材料中Fe杂质的分布,掺杂激活机理以及Fe原子与点缺陷的相互作用.原生掺Fe SI-InP中Fe的替位激活主要通过填隙-跳跃机制,但Fe原子易在位错周围聚集,与空位形成复合体缺陷,占据填隙位等,从而降低Fe的激活效率.在FeP2气氛下退火非掺InP获得的SI-InP材料中,Fe原子的激活主要通过扩散过程的"踢出-替位"机制.退火前材料中存在的In空位使Fe原子通过扩散充分占据In位,同时抑制了材料中深能级缺陷的形成.因此,这种SI-InP材料的Fe激活效率高、电学性能好.     

退火处理后非掺磷化铟的电传输特性

利用变温霍尔和电流-电压特性(I-V)两种方法分别对半导体和半绝缘的退火非掺磷化铟材料进行了测量.在非掺退火后的半导体磷化铟样品中可以测到缺陷带电导,这与自由电子浓度较低、有一定补偿度的原生非掺磷化铟的情况类似.非掺SI-InP表现出不同于原生掺铁的SI-InP的I-V特性,在一直到击穿为止的外加电场范围内呈欧姆特性,而掺铁SI-InP的I-V具有与陷阱填充有关非线性特征.根据空间电荷限制电流的理论,这种现象可以解释为非掺SI-InP中没有未被电子占据的空的深能级缺陷.     

Effect of annealing conditions on the uniformity of undoped Semi-Insulating InP

Recently, it was found that undoped semi-insulating InP can be obtained by highpressure annealing of high purity materials. The reproducibility and the uniformity was, however, not satisfactory. In the present work, we found that not only Fe concentrations but also Cr and Ni concentrations in annealed wafers were slightly increased during annealing. Since it seems that the origin of the contamination was due to the vapor source of red phosphorus, conductive InP with a trace amount of Fe was annealed under low phosphorus vapor pressure in order to reduce the contamination. By preventing the contamination of Cr and Ni, preparation of semi-insulating InP became highly reproducible. The minimum Fe concentration for realizing semi-insulating InP was found to be 1 x 10¹⁵cm⁻³. It was also found that the better resistivity uniformity can be obtained at higher annealing temperatures.     

退火处理后非掺磷化铟的电传输特性

利用变温霍尔和电流-电压特性(I-V)两种方法分别对半导体和半绝缘的退火非掺磷化铟材料进行了测量.在非掺退火后的半导体磷化铟样品中可以测到缺陷带电导,这与自由电子浓度较低、有一定补偿度的原生非掺磷化铟的情况类似.非掺SI-InP表现出不同于原生掺铁的SI-InP的I-V特性,在一直到击穿为止的外加电场范围内呈欧姆特性,而掺铁SI-InP的I-V具有与陷阱填充有关非线性特征.根据空间电荷限制电流的理论,这种现象可以解释为非掺SI-InP中没有未被电子占据的空的深能级缺陷.     

Control of low fe content in the preparation of semi-insulating InP by wafer annealing

A reproducible technique for preparing semi-insulating (SI) InP by high temperature annealing can only be achieved by controlled doping with Fe in a sufficient concentration for compensation. However, a successful and reproducible method to adjust the low Fe content has not been developed up to now. In this paper, we report two different experimental approaches to control the Fe content by using either precompensated starting material or an Fe source for doping via the vapor phase. InP wafers (2′ diam) which were lightly predoped with Fe ([Fe] < 5 × 10¹⁵ cm⁻³) during liquid encapsulated Czochralski (LEC) growth were converted from the semiconducting to the SI state and were subsequently analyzed by laterally resolved resistivity measurements. These wafers show high resistivity uniformity (p ≈1 × 10⁸ Ω-cm) which has never previously been achieved with LEC material at such a low Fe concentration. Furthermore, we present the first results of annealing nominally undoped InP with a defined Fe source.     

退火对LEC SI GaAs单晶性能的影响

本文报道了退火对非掺LEC SI GaAs晶片的电学性能和均匀性的影响。在850℃以上退火,晶片横截面上的平均迁移率由原生晶体的2.64×10~3cm~2/V·s提高到5.72×10`3cm~2/V·s,其中某些测量点达6.68×10~3cm~2/V·s,横向不均匀性由32％减少到6％,电阻率不均匀性由30％减少到10％。观察到晶片退火时间过长,性能反而下降。 基于上述实验结果,对退火改善晶体性能的机理进行了分析和讨论。     

高温退火处理提高半绝缘VGF-GaAs单晶的电学性能

垂直梯度凝固法(VGF)生长的低位错半绝缘（SI) GaAs单晶存在电阻率和迁移率低、电学补偿度小、均匀性差等问题. 在3种不同温度条件下,对VGF-SI-GaAs晶片进行了加As压的闭管退火处理. 结果表明,经过1160℃/12h的高温退火处理后,VGF-SI-GaAs单晶的电阻率、迁移率和均匀性均得到了显著提高. 利用Hall、热激电流谱（TSC) 、红外吸收法分别测试分析了原生和退火VGF-SI-GaAs单晶样品的电学性质、深能级缺陷、EL2浓度和C浓度,并与常规液封直拉法（LEC) SI-GaAs单晶样品进行了比较. 原生VGF-SI-GaAs单晶中的EL2浓度明显低于LEC-SI-GaAs单晶,经过退火处理后其EL2浓度显著增加,电学补偿增强,而且能级较浅的一些缺陷的浓度降低,因而有效提高了其电学性能.     

Characterization of deep centers in undoped semi-insulating GaAs substrates by normalized thermally stimulated current spectroscopy: Comparison of 100 and 150 mm wafers

A well-established characterization method for investigating deep traps in semi-insulating (SI) GaAs is thermally stimulated current (TSC) spectroscopy; however, TSC is not considered to be a quantitative technique because it involves carrier mobility, lifetime, and geometric factors, which are either unknown or poorly known. In this paper, we first show how to quantify a TSC spectrum, by normalizing with infrared (hv = 1.13 eV) photocurrent, and then apply this method (called NTSC) to study the lateral uniformity of the main deep centers across the diameters of undoped SI GaAs wafers. The wafers used in the study include both the standard 100 mm sizes and the new 150 mm variations, and are grown by both the low and high pressure liquid encapsulated Czochralski techniques. The results reveal that the 150 mm wafers have a worse NTSC uniformity for the main traps and a higher degree of compensation, as compared these parameters for the 100 mm wafers. In addition, nonuniformities related to the electric field effects on both the TSC spectrum and the low temperature photocurrent are found in the 150 mm wafer grown by the low pressure technique.