Carrier lifetime studies in Ge using microwave and infrared light techniques

Gaubas, E.; Bauža, Marius; Uleckas, A.; Vanhellemont, Jan

doi:10.1016/j.mssp.2006.08.023

Cited by 24 publications

(23 citation statements)

References 8 publications

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“…These carrier lifetime variations, assuming a single dominant recombination centre with energy level located nearby the mid-band-gap of Ge, imply an increase of concentration of recombination centres with increasing doping density in the as-grown Ge material. The estimated threshold value n thr is also in agreement with the saturation value obtained at the excitation density n exc of about 10 16 cm −3 as was determined for 3 Ω·cm Ge [2] using investigations of the trap filling dependence on excitation level. However, the assumption of a single dominant centre and of Shockley-Read-Hall (SRH) statistics can be used only as a first-order iteration for the study of the lifetime variation in the as-grown Ge material.…”

Section: Resultssupporting

confidence: 88%

Recombination peculiarities in doped Ge

Gaubas¹,

Uleckas²,

Vanhellemont³

et al. 2007

Lithuanian J. Phys.

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Peculiarities of recombination processes in Czochralski (Cz) grown Ge wafers of n-and p-type material are investigated. Recombination characteristics in n-Ge implanted with Co, Fe, Ti, Ni, and Cr are studied before and after annealing. A decrease of the carrier lifetime with increasing doping density has been observed both for n-and p-type Ge using the same excitation level. This decrease is analysed by assuming an increase of the concentration of recombination centres with increasing doping density. Introduction of metal impurities by ion implantation leads to a decrease of carrier lifetime values. The increase of lifetime with increasing excitation level in the metal-implanted samples implies the formation of acceptor-like slow recombination centres. A photoconductivity quenching effect has been observed in all the implanted samples indicating the existence of centres of fast recombination, related with metal implants, competing with those of slow recombination.

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Section: Resultssupporting

confidence: 88%

Recombination peculiarities in doped Ge

Gaubas¹,

Uleckas²,

Vanhellemont³

et al. 2007

Lithuanian J. Phys.

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“…The transport modeling uses the drift-and-diffusion model with doping dependent carrier mobilities and carrier densities including Shockley-Read-Hall lifetimes (SRH), 17 Auger scattering rates, 18 and optical recombination rates 19 of the different materials. The metallic contacts on the semiconductor barrier layers are set to be perfectly ohmic (i.e., infinite recombination rate at the boundaries with metal).…”

Section: Transport Modelingmentioning

confidence: 99%

“…However, it is known that the introduction of doping leads to scattering effects reducing the carrier mobilities and lifetimes. 17,26 The variation of mobilities for electrons and holes vs. doping and SRH lifetime reduction are introduced into the transport modeling following the data of Helling et al for germanium. 27 For doped silicon layers, the mobility variation is introduced following the unified model proposed by Klaassen.…”

Section: Transport Modelingmentioning

confidence: 99%

Analysis of optical gain threshold in n-doped and tensile-strained germanium heterostructure diodes

Prost

Kurdi

Aniel

et al. 2015

Journal of Applied Physics

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The optical emission of germanium-based luminescent and/or laser devices can be enhanced by tensile strain and n-type doping. In this work, we study by simulation the interplay between electrical transport and optical gain in highly n-doped and intrinsic germanium p-n heterostructure diodes under tensile strain. The effects of strain and doping on carrier mobilities and energy distribution are taken into account. Whereas the n-doping of Ge enhances the filling of the indirect L and Brillouin zone-center conduction band states, the n-doping also reduces the carrier injection efficiency, which is detrimental for the achievement of optical gain at reduced current densities. For applied biaxial strains larger than 1.25%, i.e., far before reaching the cross-over from indirect to direct band gap regime, undoped germanium exhibits a lower optical gain threshold as compared to doped germanium. We also show that the threshold current needed to reach transparency in germanium heterostructures has been significantly underestimated in the previous works.

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“…The excess carrier decay is examined as a function of the excitation level [7,8], to determine the parameters of the dominant recombination centres and mechanisms. Excess carrier decay transients are examined by combining microwave (MW) reflection (R) and absorption (A) probing of the pulsed excited area of the sample.…”

Section: Materials and Experimental Techniquesmentioning

confidence: 99%

On the Impact of Metal Impurities on the Carrier Lifetime in N-type Germanium

et al. 2007

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The impact of metallic impurities on the carrier lifetime in n-Ge is studied using microwave reflection and absorption techniques. Co, Fe, Ti, Ni and Cr are introduced by ion implantation followed by a thermal anneal and quenching to room temperature. Excess carrier decay transients are examined by microwave reflection and absorption probing after pulsed light excitation. A detailed analysis allows to evaluate the ratio of the capture cross-sections for minority and majority carriers revealing an acceptor-like character of the metal induced traps. Cross-sectional lifetime measurements show an U-shaped depth distribution with the lowest lifetimes in the bulk of the wafer. The lifetime results are correlated with those of deep level transient spectroscopy in order to clarify the properties of the dominant metal related recombination centres. Fe and Co are the most effective lifetime killers in n-Ge while Cr has the least influence.

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Carrier lifetime studies in Ge using microwave and infrared light techniques

Cited by 24 publications

References 8 publications

Recombination peculiarities in doped Ge

Recombination peculiarities in doped Ge

Analysis of optical gain threshold in n-doped and tensile-strained germanium heterostructure diodes

On the Impact of Metal Impurities on the Carrier Lifetime in N-type Germanium

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