AlGaN紫外探测器及其焦平面阵列技术研究进展

AlGaN紫外探测器及其焦平面阵列具有本征可见光盲特性,并可实现无需滤光片的日盲探测,且为全固态器件,是紫外探测技术的一个重要发展方向。文章介绍了AlGaN紫外探测器与焦平面阵列的研究现状及其存在的问题。在此基础上,分析了AlGaN雪崩光电二极管(APD)发展的基本条件,并介绍了AlGaN APD的发展现状及趋势。     

A comparative study on p-doping behavior of polythiophenes with CH<Subscript>3</Subscript>SO<Subscript>3</Subscript>H

Four kinds of polythiophenes have been doped with CH3SO3H in CHCl3 under air, oxygen, and nitrogen. In the doping of two types of poly(3-hexylthiophene)s, P3HexTh(Zn/Ni) and P3HexTh(Fe) with different contents of a head-to-tail unit, the p-doping occurs at a similar rate. The reaction between poly(3-dodecylthiophene), P3DodTh, and the acid takes place more rapidly. P3OBuTh with a butoxy substituent undergoes more facile p-doping and receives photochemical reaction with CHCl3, and this reaction obeys a pseudo-first-order rate law with a rate constant kobs of 1.42×10-5 s-1 at room temperature.     

Transition metal oxides on organic semiconductors

Transition metal oxides (TMOs) on organic semiconductors (OSs) structure has been widely used in inverted organic optoelectronic devices, including inverted organic light-emitting diodes (OLEDs) and inverted organic solar cells (OSCs), which can improve the stability of such devices as a result of improved protection of air sensitive cathode. However, most of these reports are focused on the anode modification effect of TMO and the nature of TMO-on-OS is not fully understood. Here we show that the OS on TMO forms a two-layer structure, where the interface mixing is minimized, while for TMO-on-OS, due to the obvious diffusion of TMO into the OS, a doping-layer structure is formed. This is evidenced by a series of optical and electrical studies. By studying the TMO diffusion depth in different OS, we found that this process is governed by the thermal property of the OS. The TMO tends to diffuse deeper into the OS with a lower evaporation temperature. It is shown that the TMO can diffuse more than 20 nm into the OS, depending on the thermal property of the OS. We also show that the TMO-on-OS structure can replace the commonly used OS with TMO doping structure, which is a big step toward in simplifying the fabrication process of the organic optoelectronic devices.     

Controlling the interface energetics of PCPDTBT by p-doping

The doping of organic semiconductors is a promising way for both improving the charge carrier transport and tuning the energy level alignment at interfaces. We study the influence of p-doping of the low band gap polymer PCPDTBT with F4-TCNQ on the energy level alignment in a prototype organic solar cell structure with ITO as an electrode material and the fullerene C₆₀ as electron acceptor material using Ultraviolet and X-ray photoelectron spectroscopy. As a consequence of the doping, a Quasi-Ohmic contact at the interface to ITO is formed, whereas the energy level alignment to C₆₀ is almost not affected. In contrast to a related system, we observe a depletion of the dopant at the polymer surface. The change of the energy level alignment only at the electrode interface might be advantageous for the application in organic solar cell devices.     

掺杂与Al组分对AlGaInP四元系LED发光效率的影响

在AlGaInP四元系双异质结发光二极管(DH—LED)的材料生长过程中,限制层的Al组分与P型掺杂浓度的确定有较大的随意性,这对LED的发光不利。通过分析载流子在发光二极管(LED)双异质结中的输运情况,得到了在不同的P型掺杂程度下,限制层Al组分与LED发光效率的关系,从而可以探索P型掺杂与Al组分对发光效率影响的规律,得到的结论对于LED的器件结构设计以及MOCVD材料生长有一定的指导意义。     

Effect of compensation doping on the electrical and optical properties of mid-infrared type-II InAs/GaSb superlattice photodetectors

This paper presents a theoretical study on the electrical and optical properties of mid-infrared type-II InAs/GaSb superlattices with different beryllium concentrations in the InAs layer of the active region. Dark current, resistance-area product, absorption coefficient and quantum efficiency characteristics are thoroughly examined. The superlattice is residually n-type and it becomes slightly p-type by varying beryllium-doping concentrations, which improves its electrical performances. The optical performances remain almost unaffected with relatively low p-doping levels and begin to deteriorate with increasing p-doping density. To make a compromise between the electrical and optical performances, the photodetector with a doping concentration of 3 × 1015 cm-3 in the active region is believed to have the best overall performances.     

选择性p型量子阱垒层掺杂在双波长发光二极管光谱调控中的作用

采用软件理论分析的方法对选择性p型掺杂量子阱垒层在InGaN双波长发光 二极管(LED)中的光谱调控作用进行模拟分析.分析结果表明, 选择性p型掺杂对量子阱中电子和空穴浓度分布的均衡性起到一定的调控作用, 在适当选择p型掺杂量子阱垒层层数的条件下,能够改善量子阱中载流子的 辐射复合速率, 降低溢出电子浓度,从而有效提高芯片内量子效率,并减缓内量子效率随驱动 电流增大而快速下降的趋势.随着活性层量子阱增加到特定数量, 选择性p型掺杂的调控效果更加明显, LED芯片的双波长发光峰强度达到基本均衡.     

Nitrogen doping of ZnSe by OMVPE using a novel organometallic precursor

We have investigated phenylhydrazine (PhHz) as a potential nitrogen dopant source in organometallic vapor phase epitaxial growth of ZnSe. Dimethylzinc and dimethylselenide were the zinc and selenium precursors, respectively. Photoluminescence and secondary ion mass spectroscopy measurements indicate that high incorporation efficiency compared to ammonia can be achieved using this dopant source. For example, nitrogen incorporation in the 2.5 x 10¹⁸/cm^-3 level was achieved at 350°C under ultraviolet excitation when the PhHz partial pressure was 1 x 10^-8 atm. These layers had 1-2 x lO¹⁵cm^-3 electrically active acceptors. Films grown at higher partial pressures of PhHz were highly compensated.     

Quantification of deep hole-trap filling by molecular p-doping: Dependence on the host material purity

The p-doping effect of the fluorinated fullerene C₆₀ F₃₆ doped into organic thin films of N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD) of different purification grades is systematically investigated by photoemission spectroscopy. By reducing the molar doping ratio to MR = 2.9 × 10^?4, the Fermi-level shift upon doping is resolved in particular at very low doping concentrations. In comparison to four times sublimated MeO-TPD, 5 times more C₆₀F₃₆ molecules have to be doped into unpurified MeO-TPD films to shift the Fermi-level just above its intrinsic position. This finding is discussed in terms of a statistical model, showing that narrow deep hole-trap states are additionally present in the unpurified host material which are hindering an efficient generation of free charge carriers at molar doping ratios below MR = 0.002.     

A comparative study on p-doping behavior of polythiophenes with CH_3SO_3H

Four kinds of polythiophenes have been doped with CH3SO3H in CHCl3 under air,oxygen,and nitrogen. In the doping of two types of poly(3-hexylthiophene)s,P3HexTh(Zn/Ni)and P3HexTh(Fe)with different contents of a head-to-tail unit,the p-doping occurs at a similar rate.The reaction between poly(3-dodecylthiophene),P3DodTh,and the acid takes place more rapidly.P3OBuTh with a butoxy substituent undergoes more facile p-doping and receives photochemical reaction with CHCl3,and this reaction obeys a pseudo-first-order rate law with a rate constant kobs of 1.42×10-5s-1at room tempera- ture.