InAs/GaAs自组织量子点的DLTS谱

将DLTS用于对InAs/GaAsQD结构样品的测量,测定了QD能级发射载流子的热激活能;获得了QD能级俘获电子过程伴随有多声子发射(MPE)、QD能级存在一定程度的展宽、以及在某些特定的生长条件下,存在亚稳生长构形的实验证据.结果表明:DLTS在QD体系的研究中有其特有的功能     

Investigation of the effect of CdCl2 processing on vacuum deposited CdS/CdTe thin film solar cells by DLTS

Thin film CdS/CdTe solar cells have been prepared by conventional vacuum deposition technique. Deep level transient spectroscopy (DLTS), temperature and frequency dependent capacitance-voltage (C-V) measurements were utilised to investigate the performance limiting defect states in the CdTe layer subjected to the post deposition treatments such as CdCl₂-dipping and/or annealing in air. Five hole traps, all of which have been previously reported in the literature, were identified in as-grown CdTe at 0.19, 0.20, 0.22, 0.30 and 0.40 eV above the valence band. A single hole trap level has been evidenced at 0.45 eV after both post deposition heat and CdCl₂ treatments.     

ZnO/p-Si异质结的深能级及其对发光的影响

利用深能级瞬态谱(DLTS)和光致发光谱(PL),研究了ZnO/pSi异质结的两种不同温度(850℃,1000℃)退火下的深能级中心。发现850℃退火的样品存在3个明显的深中心,分别为E₁=E_v+0.21eV,E₂=E_v+0.44eV,E₃=E_v+071eV;而1000℃退火样品仅存在一个E₁=E_v+021eV的中心,且其隙态密度要比850℃退火的大。同时,测量了两个样品的PL谱。发现1000℃退火可消除一些影响发光强度的深能级,对改善晶格结构,提高样品的发光强度有利。     

Self-interstitial solute interaction in aluminium base alloys: Problems of data interpretation

The interpretation of electrical resistivity measurement results of Al base alloys is critically discussed. Correct numerical data evaluation with respect to the atomistic properties r_c/r_p, r_t and Pf^t/Pf is yet impossible for Al and its alloys because of the overlapping of Ic and Id recovery for those electron irradiations for which damage rate measurements exist and because of the unexplained scatter of initial damage rate data.     

Direct detection of carrier traps in Si solar cells after light‐induced degradation

In solar cells fabricated from boron‐doped Cz‐Si wafers minority and majority carrier traps were detected by deep level transient spectroscopy (DLTS) after so‐called “light‐induced degradation” (LID). The DLTS signals were detected from mesa‐diodes with the full structure of the solar cells preserved. Preliminary results indicate metastable traps with energy levels positioned at E_V + 0.37 eV and E_C – 0.41 eV and apparent carrier capture cross‐sections in the 10^–17–10^–18 cm² range. The concentration of the traps was in the range of 10¹²–10¹³ cm^–3. The traps were eliminated by annealing of the mesa‐diodes at 200 °C. No traps were detected in Ga‐doped solar cells after the LID procedure or below the light protected bus bar locations in B‐doped cells. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

A deep level transient spectroscopy study on the interface states across grain boundaries in multicrystalline silicon

Degrading the recombination activities of grain boundaries (GBs) is essential to improve the efficiency of multi‐crystalline silicon (mc‐Si) based solar cells. We apply the deep level transient spectroscopy technique to detect interface states at Σ3 and Σ9 GBs in mc‐Si. The density of interface states close to midgap is found comparable for both as‐grown GBs. Gettering or hydrogenation leads to shallower states with a smaller capture cross section and lower density. Recombination activity reduction for Σ3 GBs is stronger than for Σ9 GBs especially after hydrogenation. Both the analysis approach and experimental results could be applied for a specific GB engineering of mc‐Si based solar cells. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrical characterization of deep levels in n-type GaAs after hydrogen plasma treatment

Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20-300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, E_C—0.33 eV, E_C—0.36 eV, E_C—0.38 eV and E_C—0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at E_C—0.58 eV. Isochronal annealing of the passivated material between 50 and 300 °C, revealed the emergence of a secondary defect, not previously observed, at E_C—0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 °C, as all the defects originally observed in the reference sample were recovered.     

Theory of amorphous semiconductors

The basic concepts underlying the present theory of amorphous semiconductors are reviewed. Emphasis is put on simple band models.     

DLTS and in situ C–V analysis of trap parameters in swift 50 MeV Li3+ ion-irradiated Ni/SiO2/Si MOS capacitors

Ni/SiO₂/Si MOS structures were fabricated on n-type Si wafers and were irradiated with 50 MeV Li³⁺ ions with fluences ranging from 1×10¹⁰ to 1×10¹² ions/cm². High frequency C–V characteristics are studied in situ to estimate the build-up of fixed and oxide charges. The nature of the charge build-up with ion fluence is analyzed. Defect levels in bulk Si and its properties such as activation energy, capture cross-section, trap concentration and carrier lifetimes are studied using deep-level transient spectroscopy. Electron traps with energies ranging from 0.069 to 0.523 eV are observed in Li ion-irradiated devices. The dependence of series resistance, substrate doping and accumulation capacitance on Li ion fluence are clearly explained. The study of dielectric properties (tan δ and quality factor) confirms the degradation of the oxide layer to a greater extent due to ion irradiation.     

气源分子束外延生长的InPBi薄膜材料中的深能级中心

利用深能级瞬态谱(DLTS)研究了气源分子束外延(GSMBE)生长的InP1-xBix材料中深能级中心的性质。在未有意掺杂的InP中测量到一个多数载流子深能级中心E1,E1的能级位置为Ec-0.38 e V,俘获截面为1.87×10~(-15)cm~2。在未有意掺杂的InP0.9751Bi0.0249中测量到一个少数载流子深能级中心H1,H1的能级位置为Ev+0.31 eV,俘获截面为2.87×10~(-17)cm~2。深中心E1应该起源于本征反位缺陷PIn,深中心H1可能来源于形成的Bi原子对或者更复杂的与Bi相关的团簇。明确这些缺陷的起源对于InPBi材料在器件应用方面具有重要的意义。