One of the most important parts of formulating a National Ambient Air Quality Standard is specifying the measurement methods for determining and attaining compliance. The samples taken for compliance are often pushed beyond their original purpose to identify sources, to evaluate the effectiveness of controls, and to determine relationships between pollution levels and public health. A full understanding of available sampling and analysis methods is needed, as well as an analysis of their costs, before acceptable monitoring approached can be specified. This review identifies issues related to measurement methods used to determine compliance with standards, describes current and future measurement methods and their limitations, and determines the extent to which existing technology can meet short-term and long-term needs for measuring compliance.

Measurement Methods to Determine Compliance with Ambient Air Quality Standards for Suspended Particles

We report the preparation of a CuInSe2/CdS heterojunction solar cell having a solar power conversion efficiency of 12% measured on a clear day in New Jersey (∼92‐mW/cm2 solar intensity).

Efficient CuInSe2/CdS solar cells

Hopping conductivity in ordered and disordered solids (II)

Transport properties of CuInSe2

Cellule solaire a film mince amelioree, a grande surface, procedes et appareil de fabrication de cette cellule, cette derniere possedant un rendement de conversion lumiere-energie electrique relativement eleve et caracterisee en ce que la cellule (30) comprend une heterojonction (34) du type pn formee i) d'une premiere couche semi-conductrice (35) comprenant un materiau presentant une activite photovoltaique choisie dans les materiaux de la classe des chalcopyrites I-III-VI2 ternaires qui est deposee sous la forme d'une couche mince a 'gradient de composition' dont l'epaisseur est de l'ordre d'environ 2,5 microns a 5,0 microns (= 2,5 (Alpha)ma 5,0 (Alpha)m) et dans laquelle la region inferieure (35a) du materiau photovoltaique comprend de preference une region de basse resistivite de materiau semi-conducteur du type p superposee par une region (35b) de resistivite relativement haute, un materiau semi-conducteur de transition du type n definissant une homojonction de transition pn; Thin film solar cell has improved has large area, processes and manufacturing apparatus of this cell, the latter possessing an electric light-energy conversion efficiency relatively high and is characterized in that the cell (30) comprises a heterojunction (34) Type pn FORMED i) a first semiconductor layer (35) comprising a material having demonstrated a photovoltaic activity in the materials selected from the class of chalcopyrite I-III-VI2 ternary which is deposited as a thin layer 'composition gradient' whose thickness is of the order of about 2.5 microns to 5.0 microns (= 2.5 (Alpha) my 5.0 (Alpha) m) and wherein the lower region ( 35a) of the photovoltaic material preferably comprises a region of low resistivity semiconductor material of p-type superimposed by a region (35b) of relatively high resistivity, transition semiconductor material of n-type defining a transition pn homojunction; et ii) d'une seconde couche semi-conductrice (36) comprenant un materiau semi-conducteur a basse resistivite du type n; and ii) a second semiconductor layer (36) comprising a semiconductor material has low resistivity n-type; l'interdiffusion a) entre les constituants elementaires entre les deux regions discretes juxtaposees de la premiere couche semi-conductrice (35) definissant une couche de transition d'homojonction pn et b) entre le materiau de transition de type n dans la premiere couche semi-conductrice (35) et la deuxieme couche semi-conductrice (36) du type n, provoque la conversion du materiau de transition du type n dans la premiere couche semi-conductrice (35) en materiau de type p, definissant ainsi un dispositif a film mince a heterojonction caracterise par l'absence de vides, de lacunes et de nodules qui tendent a reduire le rendement de conversion du systeme. interdiffusion a) between the elementary constituents between the two juxtaposed discrete regions of the first semiconductor layer (35) defining a transition layer of pn homojunction and b) between the n-type transition material in the first semiconductor layer -conductrice (35) and the second semiconductor layer (36) of n-type material causes the conversion of n-type transition in the first semiconductor layer (35) in p-type material, and defining a device thin film characterizes HETEROJUNCTION by the absence of voids, gaps and nodules which tend to reduce the system conversion efficiency.

Methods and apparatus for forming thin-film heterojunction solar cells from i-iii-vi2 chalcopyrite compounds, and solar cells produced thereby

X-ray data is presented and analysed for the semiconducting compound CuInSe2, prepared by zone levelling. Values of a = 5.782 and c = 11.620 A, have been determined and intensity calculations have been used in the evaluation of interatomic separation and bond angles. Some aspects of stoichiometry, related to electrical characteristics, are discussed and it seems probable that the structure of the compound is modified by a small concentration of Se vacancies.

Crystal data for CuInSe2

Various bulk electrical properties and device characteristics have been measured. It has been shown that the majority carrier type is dependent on crystal stoichiometry. Mobilities of 660 cm2/V sec and 30 cm2/V sec have been measured for n-and p-type samples, respectively. Rectifying contacts and p-n junctions have been investigated by small signal analysis and the associated doping levels and equilibrium band diagrams have been determined. Photovoltage measurements on rectifying contacts have shown that the band-gap has a value of 0.95 ± 0.01eV.

Electrical properties of CuInSe2 single crystals

Some properties of flash evaporated CuInSe2 thin films

Data are given of the hall mobility, carrier concentration and conductivity for epitaxial, polycrystalline, and amorphous Ge films over a temperature range 100 to 400 K; all specimens are found to be p-type. The room temperature noise spectra for these films are also given. It is found that amorphous films can be characterised by the presence of generation–recombination noise with time constants of 4.5 × 10−3 and 2 × 10−5 s wheras in crystalline films only 1/f noise is present. An activated mobility was found for unannealed amorphous films and the data agrees with present theories remarkably well except that the apparent hole concentration falls with a rise in temperature.



Es werden Werte fur die Hallbeweglichkeit, die Ladungstragerkonzentration und Leitfahigkeit fur epitaktische, polykristalline und amorphe Ge-Schichten in. Temperaturbereich von 100 bis 400 K mitgeteilt; alle Proben waren p-leitend. Dazu werden die Rauschspektren dieser Schichten fur Zimmertemperatur angegeben. Es wird gefunden, das die amorphen Schichten durch Generations–Rekombinationsrauschen charakterisiert sind mit Zeitkonstanten von 4,5 × 10−3 und 2 × 10−5 s, wahrend in den kristallinen Schichten nur 1/f-Rauschen auftritt. Fur ungetemperte amorphe Schichten wird eine aktivierte Beweglichkeit beobachtet, wobei die Werte mit existierenden Theorien bemerkenswert gut ubereinstimmen, bis auf die Tatsache, das die scheinbare Locherkonzentration mit steigender Temperatur abnimmt.

M.J. Hampshire

Papers

Crystal data for CuInSe2

Electrical properties of CuInSe2 single crystals

Some properties of flash evaporated CuInSe2 thin films

Hall effects and noise measurements in epitaxial, polycrystalline, and amorphous Ge

Charge build-up in ice layers condensing on liquid nitrogen traps