Study of GeYSi1−Y:H films deposited by low frequency plasma

Sanchez, L.; Kosarev, A.; Torres, Alfonso; Il’inskiĭ, A. V.; Kudriavtsev, Yu.; Asomoza, R.; Cabarrocas, Pere Roca i; Абрамов, А.

doi:10.1016/j.tsf.2006.11.100

Cited by 7 publications

(9 citation statements)

References 9 publications

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“…Figure 1 shows for comparison the spectral dependence of the optical absorption coefficient α(hυ) for intrinsic HT Ge:H and intrinsic HT and LT Ge 0.96 Si 0.04 :H films. For details about band tail and defect absorption for the selected films, see [2].…”

Section: Methodsmentioning

confidence: 99%

“…These films can be used for different device applications i.e., solar cells [1]. Previously the films with low density of localized states obtained by low frequency (LF) PECVD at deposition temperature T d = 300°C has been reported [2] and doping of these films has been discussed [3]. To our knowledge fabrication and characterization of Ge y Si 1-y :H films with high Ge concentration (y>0.5) obtained by low temperature plasma deposition and n-type and p-type doped films is poorly reported in literature [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

et al. 2012

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In this work we present the results of comparative study n-and p-doping of Ge:H and Ge 0.96 Si 0.04 :H films deposited by LF PECVD at high deposition temperature (HT) T d =300°C and low deposition temperature (LT) T d =160°C. The concentration of boron and phosphorus in solid phase was measured by means of SIMS technique. Such parameters as spectral dependence of absorption coefficient, room temperature conductivity σ RT and activation energy E a for both intrinsic and doped films were obtained. The doping range studied in gas phase was for boron [B] gas = 0 to 0.15% and for phosphorus [P] gas = 0 to 0.2%. In general effect of deposition temperature on P and B doping has been demonstrated. For LT films changes of [P] gas =0.04% to 0.22% resulted in more than 2 orders increasing conductivity and reducing activation energy from E a =0.28 to 0.16 eV. HT films in the range of [P] gas =0.04% to 0.2% demonstrated saturation of conductivity. HT films showed continuous reducing E a with increase of [P] gas . In the case of boron doping both HT and LT films had a minimum of conductivity at certain values of [B] gas =0.05% (LT films) and 0.04% (HT films) and related maximums of activation energy E a(max) at the same doping with E a(max) =0.47 eV for HT and E a(max) =0.53 eV for LT films. It suggests a compensation of electron conductivity in un-doped films for low B doping. Further raising [B] gas leads to reducing E a and the smallest E a =0.27 eV was obtained at [B] gas =0.18% for HT films and E a =0.33 eV at [B] gas =0.14% for LH films.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

et al. 2012

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Phosphorous and Boron Incorporation and Its Effect on Electronic and Optical Properties of Ge:H Films Deposited by LF Plasma

Delgadillo

Kosarev

Torres

et al. 2010

2010 IEEE Electronics, Robotics and Automotive Mechanics Conference

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In a previous work [1], the deposition conditions that provided low optical absorption related to both band tail and deep localized states have been found for both materials Ge:H and Si 1-Y Ge Y :H. In this work phosphorous and boron doping of Ge:H films have been systematically studied. These films were deposited by low frequency (LF) plasma under the conditions for low density of localized states whit optimal hydrogen dilution. The deposition parameters were as follow: substrate temperature Ts= 300 °C, discharge frequency f= 110 kHz, pressure P= 0.6 Torr, power W= 300 W, and the flow gas for the films of Ge:H was; germane flow QGeH 4 = 50 sccm, hydrogen flow QH 2 =2500 sccm, the phosphine flow was varied in the range of QPH 3 = 20 to 100 sccm providing phosphorous concentration in gas phase in the range of X P = 4 to 20 %. For boron we used the same conditions as before, but the B 2 H 6 flow was varied in the range of QB 2 H 6 = 3 to 20 sccm providing concentration in gas phase in the range of X B = 0.3 to 4 %. SIMS profiling was used for determining the composition of the doped films. The hydrogen bonding was studied by FTIR. The temperature dependence of conductivity measured in DC regime was performed in a vacuum thermostat in order to study carrier transport. Optical measurements provided optical gap, absorption and refraction index. The Phosphorous incorporation to the solid film demonstrated that for the doping conditions used in this work, we obtained a constant P concentratio. But for boron incorporation, the concentration of it in the solid films increases linearly with its concentration in the gas phase. The influence of the P and B doping on the hydrogen concentration, activation energy and conductivity of the films is also studied and presented.

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“…It has been also demonstrated that Ge x Si 1-x :H films with x>0.95 have shown superior electronic properties in comparison with those in Ge:H films having practically the same optical gap [4][5][6].…”

Section: Introductionmentioning

confidence: 98%

“…Some devices with Ge:H films have been reported [1,2], where Ge:H was used as the intrinsic layer in p-i-n structures, however, doped nand p-layers were fabricated of silicon. In our previous studies [4,5] we have demonstrated a LF PECVD fabrication of Ge:H and Ge x Si 1-x :H films with both low tail and deep localized states. In this respect low frequency (LF) PECVD with its inherent higher ion bombardment than that in conventional RF plasma is very attractive.…”

Section: Introductionmentioning

confidence: 99%

Sub-gap Photoconductivity in Germanium-silicon Films Deposited by Low Frequency Plasma

Kosarev

Avila

2010

MRS Proc.

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Ge x Si 1-x :H) films are of much interest for many device applications because of narrow band gap and compatibility with films deposited by plasma. However, electronic properties of Ge x Si 1-x :H films for high Ge content x > 0.5 have been studied less than those of Si films. In this work, we present a study of sub-gap photoconductivity (σ pc ) in Ge x Si 1-x :H films for x = 1 and x = 0.97 deposited by low frequency plasma enhanced chemical vapor deposition (LF PECVD) with both various H-dilution (R H ) during growth (non-doped films) and boron (B) incorporation in the films. Spectra of sub-gap photoconductivity σ pc (hν) were measured in the photon energy range of hν = 0.6 to 1.8 eV. σ pc (hν) spectra were normalized to constant intensity. For hν < E g two regions in σ pc (hν) can be distinguished: "A", where σ pc is related to transitions between tail and extended states, and "B", where photoconductivity is due to defect states. σ pc (hν) in "A" region showed exponential behavior that could be described by some characteristic energy E U PC similar to Urbach energy E U in spectral dependence of optical absorption. E U PC > E U was observed in all the films studied. This together with higher relative values (i.e. normalized by the maximum value at hν = E g ) for photoconductivity comparing with those for α means that mobility-lifetime product (µτ) depends on photon energy µτ = f(hν) that was determined from α(hν)and σ pc (hν). µτ(hν) increases by factor of 20 to 40 depending on the sample with reducing hν from 1.1 to 0.7 eV. In some samples, this dependence was monotonous, while in others demonstrated maxima related to both interference and density of states. Effects of both R H and boron incorporation have been found and are discussed.

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Study of GeYSi1−Y:H films deposited by low frequency plasma

Cited by 7 publications

References 9 publications

Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

Phosphorous and Boron Incorporation and Its Effect on Electronic and Optical Properties of Ge:H Films Deposited by LF Plasma

Sub-gap Photoconductivity in Germanium-silicon Films Deposited by Low Frequency Plasma

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Study of GeYSi1−Y:H films deposited by low frequency plasma

Cited by 7 publications

References 9 publications

Comparison of Doping of Gey Si1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

Comparison of Doping of Gey Si1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

Phosphorous and Boron Incorporation and Its Effect on Electronic and Optical Properties of Ge:H Films Deposited by LF Plasma

Sub-gap Photoconductivity in Germanium-silicon Films Deposited by Low Frequency Plasma

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Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures

Comparison of Doping of Ge_y Si_1-y:H (y>0.95) Films Deposited by Low Frequency PECVD at High (300°C) and Low (160°C) Temperatures