Minority carrier transport in carbon doped gallium arsenide

Abstract

Minority carrier electron mobilities and diffusion lengths in p-type C-doped GaAs have been measured at room temperature and 77 K using the zero field time of flight (ZFTOF) technique on p+–n structures with p+ carrier concentrations of 1.1×1019, 6.0×1018, 1.8×1018 cm−3, which were grown by low-pressure metalorganic chemical vapor deposition (MOCVD) using CCl4 as the dopant. The electron mobilities obtained are higher than those reported for Be-doped MBE GaAs but lower than those reported for Ge-doped, LPE GaAs, while the diffusion lengths are similar to those found in similar concentration Be-doped samples.

Central role of electronic temperature for photoelectron charge and spin mobilities in p+-GaAs

“…At T L ¼ 300 K, l e ¼ 1560 cm 2 V À1 s À1 , in excellent agreement with the theoretical value of 1643 cm 2 V À1 s À1 at similar doping densities predicted by Bennett 15 and with the existing experimental data. 1,9,10,16 The spin mobility l s was measured using a similar approach by using a circularly polarized excitation and a quarter wave plate followed by a linear polarizer at the reception, thus yielding the profile of the spin concentration s ¼ n þ À n À , where n 6 is the concentration of electrons of spin 6, with a quantization axis along the direction of light excitation. 11 The equation for s is similar to Eq.…”

“…4,5 The hole mobility at room temperature, l h ¼ 202 cm 2 V À1 s À1 , as well as its $T 1=2 L temperature dependence below 100 K are in good agreement with previous reports on similarly doped GaAs. 5,9,10 Spin-polarized photoelectrons were generated by a tightly focussed circularly polarized CW laser excitation (1/e half width of 0.6 lm, energy 1.59 eV unless otherwise stated) in a setup described elsewhere. 11 A maximum excitation power of 0.01 mW produces a non degenerate photoelectron concentration of $5 Â 10 14 cm À3 in the steady state.…”

Back Illuminated N/P/P<sup>+</sup> Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

“…2) The generation of electrical charge carriers, at a depth x, is the appearance of electrical charges (electrons and holes) in the material, represented by the relationship of generation rate (G(x)) related to the spectral quality of incident light, constant flow [12] or variable i.e. modulated frequency [13] [14] [15] [16] [17] or pulsed [18] [19] [20] [21]. Depending on the architecture of the structure, the incident flow may be perpendicular to the front [22] [23] or back [24] [25] surface of the base.…”

Anomalous reduction in the energy loss of electrons in p-type semiconductors

“…3,5 In the high doping regime, to our knowledge, the dependence of the energy loss on doping concentration has not been investigated until now. The behavior of the electron mobility and momentum relaxation is known from transport measurements [9][10][11] and theoretical calculations. 12,13 However, no direct observation of the femtosecond energy relaxation of minority electrons has been reported for doping concentrations above pϾ2ϫ10 19 cm Ϫ3 .…”