Investigation of the influence of doping on field quenching in CdS

Hadley, H. C.; Voss, P.; Böer, Karl W.

doi:10.1002/pssa.2210110259

Cited by 14 publications

(3 citation statements)

References 6 publications

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“…Thereby other observations that are based on the current behavior alone can now be more precisely categorized. This is especially helpful in CdS, where the conductivity can independently be influenced by the light intensity, temperature, and doping [32]. A wealth of information is available from the movie [16] that is attached to the Springer book on the Visualization of Field and Current Distributions in Semiconductors [40].…”

Section: Figurementioning

confidence: 99%

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

Böer

2012

Physica Status Solidi (b)

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It is shown that stationary high-field domains that occur in the range of negative differential conductivity, can be used to clearly identify field-quenched states in CdS. These are distinguished as cathode and anode-adjacent domains and permit an unambiguous determination of electron density and mobility as function of the electric field. The anode-adjacent domain permits additional insight into the high-field properties of CdS in a field range that is now stabilized in the prebreakdown range. Here one finds direct evidence, by using the spectral distribution of the photoconductivity within the domain, of inverting the CdS to p-type either by more complete quenching or by hole injection from the anode. Both types of stationary domains are determined by the work function of blocking contacts and thereby permit a closer analysis of the contact/CdS interface by shifting the space charge region away from the cathode to the bulk-side end of the domain. This allows a more precise determination of the dependence of the work function on the photoconductivity of the adjacent CdS. The field-of-direction (phase portrait) analysis of the time-independent transport and Poisson equations allows a simple classification of the two types of stationary high-field domains relating to the two singular points in the decreasing branch of the current-voltage characteristic. This permits a transparent discussion of the field distribution of these domains that can be directly observed by the Franz-Keldysh effect. Herewith the transition between cathode-to anode-adjacent domains as a function of the applied voltage can be directly followed.

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Section: Figurementioning

confidence: 99%

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

Böer

2012

Physica Status Solidi (b)

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“…For this, the density of Coulomb-attractive hole centers, that is caused by copper doping, has to be large enough. However, if the centers are too close to each other, their Coulomb funnels overlap too much, and cause a rapid increase in the field that is necessary to initiate Frenkel-Poole excitation [44]. There is a steep optimum for the copper density in CdS of about 50 ppm (see Fig.…”

Section: Why Is Only Cds Such An Advantageous Cover-layer?mentioning

confidence: 99%

The importance of gold‐electrode‐adjacent stationary high‐field Böer domains for the photoconductivity of CdS

Böer

2015

Annalen der Physik

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When the electron density decreases stronger than linearly with the electric field in photoconductive CdS due to field quenching, high-field domains must occur that remain attached to either the cathode or anode in slit electrode geometry with blocking cathodes. These Böer domains 1 are easily seen by their shift in optical absorption due to the Franz-Keldysh effect and offer unique opportunities to analyze field dependent parameters within the range of constant electron density and electric field, such as the carrier density or mobility as a function of the field, and give information of the light dependent work function. They also provide insight why a 200Å thick cover layer of CdS on top of a CdTe solar cell increases its efficiency from 8 to 16% . The behavior of these Böer domains escapes conventional current voltage analyses except for their visual observation, while other high-field domains with their current fluctuations or oscillations are easily observed and are the subjects of thousands of publications and many books. In this review we will exclude detailed discussion of dynamic domains, but include some new specifics that help to understand the mechanisms of the Böer domains and their applications. Only properties at low optical excitation intensities are discussed that exclude Joules heating. Within the p-type regime of the anode-adjacent domain extremely steep electronic quenching signal becomes visible that could signalize an intrinsic donor level slightly above the middle of the band gap that may be responsible for not allowing CdS to ever become ptype by doping.

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“…It should be emphasized that the space charge reduction via field-quenching discussed here is closely related to the high-field domain work reported earlier [18] and summarized in [19], except that in this earlier work total compensation (reduction of the space charge to zero) was assumed. First results of influences of doping on such domains are reported in [20]. Even though this work was performed on CdS single crystals sensitized with Ag and illuminated with a substantially lower monochromatic photon flux, it appears that a very similar behavior can be deduced in the photoconductive (sensitized with Cu) junction region of the CdS/Cu,S solar cell [21], and that it is probably this field quenching which permits utilization of CdS of medium purity, as the field is limited preventing tunneling to deteriorate the characteristics, as indicated below.…”

Section: Space Ehavge and Field Limitation Caused By Field Quenchingmentioning

confidence: 99%

The CdS/Cu2S solar cell. II. The junction and junction-emitter relation

Böer

1981

Phys. Stat. Sol. (a)

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Investigation of the influence of doping on field quenching in CdS

Cited by 14 publications

References 6 publications

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

The importance of gold‐electrode‐adjacent stationary high‐field Böer domains for the photoconductivity of CdS

The CdS/Cu2S solar cell. II. The junction and junction-emitter relation

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