Lifetime Profile Research Articles

Lifetime profiles of earnings and employment: A survey

Lifetime profiles of earnings and employment: A survey

Uncertainty and the Accumulation of Human Capital Over the Life Cycle

Models of the accumulation of human capital over the life cycle have recently received widespread attention in the literature on labor economics. The seminal work by Becker (1964) and Ben-Porath (1967) characterized optimal investments in education and the resulting lifetime profiles for both human capital and labor income. More recent refinements by Ghez and Becker (1975), Blinder and Weiss (1976), and Heckman (1976) added consumption and leisure, thereby altering predicted patterns for labor supply and labor earnings. Simultaneously, empirical stLudies by Mincer (1974), Haley (1976), Rosen (1976), and others used the current theory to estimate relevant parameters affecting labor earnings over the life cycle. Despite this lengthy literature on human capital, existing research has largely ignored all significant sources of uncertainty affecting observed behavior over the life cycle.' This is unfortunate if only because the introduction of uncertainty significantly alters predicted patterns for both labor supply and labor earnings. For Existing models of the accumulation of human capital over the life cycle ignore uncertainty. In this paper proper-ties of optimal allocations to labor, leisure, and education over the life cycle are developed in detail for the individual facing uncertainty from several soul-ces. Results are reported for both a simple stochastic model and a more general adaptive model in which the individual, by investing in education, not only accumulates hUman capital but also gradually learns about his ability to acquire additional huLman capital.

On the theory of dynamic input-output models with different time profiles of capital construction and finite life-time of capital equipment

On the theory of dynamic input-output models with different time profiles of capital construction and finite life-time of capital equipment

Measurement of carrier lifetime profiles in diffused layers of semiconductors

This paper describes a method for the measurement of carrier generation lifetime profiles within diffused layers in semiconductors. Knowledge of the lifetime distribution is the key to being able to accurately predict terminal electrical properties as well as understanding the physical processes operating in devices. In addition, the lifetime profile should be a sensitive measure of the quality of the device processing. Although many methods have been developed and applied to the measurement of lifetime in uniformly doped semiconductor regions, this is the first time that lifetime profile measurements have been achieved within diffused layers. In this paper, the lifetime measurements were done by the ZERBST technique using an MOS capacitor created by anodization of the wafer surface. The use of ZERBST plots allows the easy separation of surface recombination from the bulk lifetime eliminating one major source of error during lifetime measurements. In addition, the MOS capacitor used for the lifetime measurement can also be used for the measurement of the carrier concentration allowing excellent correlation between the lifetime and the doping concentration. The anodization techniques used for these measurements allow the stripping of small sections of even shallow diffused layers providing good depth resolution during the profiling. Using this method of lifetime profiling, lifetime measurements have been made up to concentrations of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> atoms/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in both n- and p-type diffused layers in silicon.

Profile of the carrier lifetimes in illuminated GaAs as a function of depth

The carrier lifetimes τ of illuminated semiconductors depend on the depth due to surface-recombination effects. In this paper the existence of this effect has been proven. The method is based on measurements of mean lifetimes ? as they are obtained from photoconductivity and the photomagnetoelectric effect for various penetration depths z of the illuminating irradiation. The form of the plots ?=f (z) is found to depend on the ratio of the ambipolar length over the Debye length showing a minimum of ? for La?lD (where La is the ambipolar diffusion length and lD is the Debye length). The results can be explained on the basis of a profile of carrier lifetime versus depth which has a minimum near the surface. Its position depends on the light penetration and, of course, on the surface-recombination velocity.

The fluorocarbon-ozone theory—IV. Fluorocarbon mixing and photolysis. The effects of eddy diffusion and tropospheric lifetime on stratospheric odd chlorine mixing ratios

Odd chlorine concentrations in the stratosphere arising from CCl 2F 2 and CCl 3F are calculated using a one-dimensional model of diffusion and photolysis together with accurate production and release data. Odd chlorine mixing ratios are mapped as a function of eddy diffusion profile and tropospheric lifetime. The results allow quick conversion of ozone depletion estimates, obtained from complete one-dimensional modelling, from a given assumed tropospheric lifetime and diffusion profile to other assumed lifetimes. In addition to contributions to CIX from CCl 2F 2 and CCl 3F, contributions from other chlorocarbons which have been detected in the troposphere, are assesssed. Our calculated estimate for the currently expected (January, 1977) total stratospheric CIX level is 1.5 ppb. Assuming there are no major calibration problems with current stratospheric CIX measurements, the measured stratospheric C1X levels are higher than calculated suggesting the possibility of other unidentified chlorine sources.

Profiles of recombination and transport parameters in thin sos films

SOS film properties are investigated by galvanomagnetic effects which are dominated by either recombination or transport phenomena. The magnetodiode effect allows to obtain both the surface recombination velocities and the bulk lifetime profile : the decrease of the carrier bulk lifetime by an order of magnitude near the Sapphire accounts for the relatively moderate recombination velocity obtained at the Si/Sapphire interface (s ~ 20 to 30 ms-1). Bulk Hall measurements are used, besides the determination of mean drift and Hall mobilities, to study the transport inhomogeneities; a linear decrease of the mobility with the distance from the Si/SiO2 interface would lead to a relatively large electron mobility near this interface (|03BCn| ~ 0.1 m2 V-1 s-1).

Measurement of minority carrier lifetime profiles in silicon

The influence of finite surface recombination velocity on the measurement of minority carrier lifetime has been studied. The method is based on measuring the phase shift between the a.c.-photocurrent of a Schottky contact and the incident light. The limit of spatial resolution has been shown by theoretical calculations to be about one diffusion length. Lifetime profiles have been measured by the use of a mercury capillary contact.

Measurement of minority carrier lifetime profiles in silicon : G. Schwab, H. Bernt and H. Reichi. Solid-St. Electron.20, p. 91 (1977)

Measurement of minority carrier lifetime profiles in silicon : G. Schwab, H. Bernt and H. Reichi. Solid-St. Electron.20, p. 91 (1977)

The effective lifetime profiles of the [formula omitted] and N 2+ (B 2⩞ u+, v = 0) excited species

The height variation of the effective lifetimes of the 1 S state of O and (B 2∑ u +, v = 0) level of N 2 + in the atmosphere are calculated. For the excited N 2 + ions the half quenching height is found at 48 ± 4 km, giving the possibility of observing N 2 + first negative band emissions below 50 km in relativistic particle events. The half quenching height of the O( 1S) atoms is found to vary between 85 and 115km, depending on different values of the quenching rate coefficients and model atmospheres. Quenching, therefore, has a different effect on the 4278 and 5577 Å emission height profiles when auroral particles penetrate into and below the E-region.

A NAIVE HISTORY OF INDIVIDUAL INCOMES IN WISCONSIN, 1947–1959

The paper develops a descriptive history of the changing level and sources of income of the male population of Wisconsin from 1947 to 1959, as a preliminary step in building a model of income determination. The history is based on data from a one percent sample of the taxpaying population of Wisconsin from 1947 to 1959. Analysis of income sources received by male birth cohorts is followed by summary data on individual income variation.Changes in earnings of birth cohorts appear to be determined by changes in labor force participation, general productivity increases, and acquisition of skills. Education, as reflected in occupational status, appears to affect the initial level and lifetime profile of earnings; however, education has played a changing role in the dynamics of earnings.Movements in non‐earned income appear to be determined by rising real yields on capital, accumulation of wealth, and possibly by asset conversion and selective migration and mortality favoring wealth holders. Cohort asset accumulation for the period seems to have been determined by the growth rate of earnings, life cycle contingencies, and the pattern of asset prices and yields during the period.Analysis of individuals’ incomes over the period reveals great heterogeneity of experience of individuals within birth cohorts and within occupations. This suggests that study of micro units is necessary to obtain behavioral information obscured in aggregate cohort data.