Enhanced Dark Current Suppression of Amorphous Selenium Detector With Use of IGZO Hole Blocking Layer

Abbaszadeh, Shiva; Tari, Alireza; Wong, William S.; Karim, Karim S.

doi:10.1109/ted.2014.2341249

Cited by 16 publications

(4 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, it is better to use metal oxide as the hole blocking layer under these circumstances [87]. Abbaszadeh and her team showed that Indium Gallium Zinc Oxide (IGZO) is an appealing choice [88]. The IGZO provides an exceptional reduction of dark current.…”

Section: Charge Injection Blockingmentioning

confidence: 99%

Recent Developments of Amorphous Selenium-Based X-Ray Detectors: A Review

Huang

Abbaszadeh

2020

IEEE Sensors J.

Self Cite

View full text Add to dashboard Cite

Amorphous selenium (a-Se) is a photoconductive material that has been intensively investigated from its early application in xerography to its present application in flat panel X-ray imagers. It can be deposited up to a few millimeters thick over a large area. Its high vapor pressure yields uniform coverage in novel device structures for lowcost and large-area applications. The evidence of avalanche multiplication in a-Se and application of a-Se in high-gain avalanche rushing photoconductor video-tubes goes back to the early 1980s. Over the past decade there has been increasing research interest in novel detector structures and integration of a-Se with new materials to leverage the avalanche properties. We summarize some of the shortcomings of a-Se such as low charge carrier mobility, low charge conversion efficiency, depth dependence, and high dark current at high electric fields. We then highlight recent developments in a-Se-based devices to address these shortcomings and enable picosecond timing performance and high detection efficiency.

show abstract

Section: Charge Injection Blockingmentioning

confidence: 99%

Recent Developments of Amorphous Selenium-Based X-Ray Detectors: A Review

Huang

Abbaszadeh

2020

IEEE Sensors J.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The excessive dark current has been one of the factors that limits the highest operating field in X-ray photoconductors. An acceptable level of dark current up to the electric field as high as 60 V/m in some detector structures has recently been reported [5]. Moreover, at a very high field (above ϳ70 V/m), holes in a-Se can gain enough energy to create additional electron and hole pairs through impact ionization with a useful avalanche gain of 1000 or more [6].…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of temperature- and field-dependent effective drift mobilities and impact ionization coefficients in amorphous selenium

Hijazi

Kabir

2015

Can. J. Phys.

View full text Add to dashboard Cite

The mechanisms of electric-field-and temperature-dependent effective drift mobility and impact ionization coefficient of both holes and electrons in amorphous selenium (a-Se) are investigated in this paper. An analytical model for the microscopic mobility, momentum relaxation mean free path, and hence the effective drift mobility and impact ionization coefficient of carriers, is proposed in this paper by considering the density of states distribution, field enhancement release rate from the shallow traps, and carrier heating. The results of the model are fitted with the published experimental results on effective mobility and impact ionization coefficient with wide variations of the applied electric field and temperature. A better fitting considering thermally activated tunneling for the field-enhancement release rate indicates that the effective drift mobility at extremely high fields is mainly controlled by the neutral defect states near the band edges. The density of state function near the band edges, consisting of an exponential tail and a Gaussian peak, can successfully describe the electric-fieldand temperature-dependent effective drift mobility characteristics in a-Se. The momentum relaxation mean free path decreases with increasing field and decreasing temperature, which is required to describe the electric-field-and temperature-dependent behaviors of impact ionization coefficient in a-Se. PACS Nos.: 72.20.Jv, 72.20.Ht, 71.23.An.Résumé : Nous étudions ici les mécanismes de dépendance en champs électriques et en température de la mobilité de dérive efficace et du coefficient d'ionisation par impact des trous et des électrons dans le sélénium amorphe (a-Se). Nous tenons compte de la distribution de densité d'états, de la libération du renforcement du champ des pièges peu profonds et du réchauffement des porteurs, afin de proposer un modèle analytique pour la mobilité microscopique, le libre parcours moyen de relaxation d'impulsion et ainsi la mobilité de dérive efficace et le coefficient d'ionisation par impact. Les résultats du modèle sont ajustés avec les résultats expérimentaux publiés sur la mobilité efficace et le coefficient d'ionisation par impact avec de grandes variations du champ électrique et de la température. Un meilleur ajustement qui tient compte d'un effet tunnel dans la libération de renforcement du champ indique que la mobilité de dérive aux valeurs élevées de champ est surtout contrôlée par les états défauts près des bords de bande. La fonction de densité d'états près du bord de bande qui consiste en un pic gaussien et une queue exponentielle peut décrire avec succès les caractéristiques de la dépendance sur le champ électrique et la température de la mobilité de dérive dans le a-Se. Le libre parcours moyen de relaxation de l'impulsion diminue lorsque le champ croît et que la température baisse, ce qui est nécessaire pour décrire correctement la dépendance en température du coefficient d'ionisation par impact dans a-Se. [Traduit par la Rédaction]

show abstract

“…Various a-Se-based photodetector structures with different HBLs have been proposed and investigated [21], [22], [23], [24], [25]. As an example, in HARP TV camera tubes, nanometer-thin films of cerium oxide (CeO 2 ) have been utilized as an HBL [26], [27], [28].…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of an Amorphous Selenium Photodetector at High Fields for Application Integration

et al. 2023

Self Cite

View full text Add to dashboard Cite

Polyimide (PI) has been utilized as a hole-blocking layer (HBL) in high-resistivity photoconductors such as amorphous selenium (a-Se) and amorphous lead oxide (a-PbO). It prevents hole injection from the positively biased electrode and suppresses the dark current of the detector. To determine the performance parameters of an a-Se/PI detector for readout design and specification for different radiation detection applications, knowledge of the accurate voltage drop within the photoconductor is crucial. Here, we precisely determine the voltage drop across a-Se when interfaced with a thin layer of PI (1 µm) and characterize its temporal resolution (rise time and jitter), dynamic range, and quantum efficiency (QE) as a function of the electric field. The photoresponse of the detector is characterized using light-emitting diodes in the ultraviolet (UV, 355-400-nm wavelength) and visible (400-533-nm wavelength) regions of the light spectrum. We find the voltage drop across a-Se as 91% of the total applied voltage. This results in a QE near unity at 405 nm for corrected fields beginning at 45 V/µm. At fields of 50 V/µm, we observe rise times of 3.7 ns and jitter of 130 ps.

show abstract

Enhanced Dark Current Suppression of Amorphous Selenium Detector With Use of IGZO Hole Blocking Layer

Cited by 16 publications

References 13 publications

Recent Developments of Amorphous Selenium-Based X-Ray Detectors: A Review

Recent Developments of Amorphous Selenium-Based X-Ray Detectors: A Review

Mechanisms of temperature- and field-dependent effective drift mobilities and impact ionization coefficients in amorphous selenium

Performance Evaluation of an Amorphous Selenium Photodetector at High Fields for Application Integration

Contact Info

Product

Resources

About