摘要:
Photovoltaic devices (e.g., solar cells) are disclosed that include at least three radiation absorbing layers, each capable of absorbing radiation over a different wavelength range of the solar radiation spectrum. Any two of these three wavelength ranges can be partially overlapping, or alternatively they can be distinct. The layers are disposed relative to one another so as to form two junctions, each of which includes a depletion region. In some cases, the radiation absorbing layers can collectively absorb radiation over a wavelength range that spans at least about 60%, or 70%, or 80%, and preferably 90% of the solar radiation wavelength spectrum. By way of example, in some embodiments, one layer can exhibit significant absorption of solar radiation (e.g., it can absorb at least one radiation wavelength at an absorptance greater than about 90%) at wavelengths less than about 0.7 microns while another layer can exhibit significant absorption of the solar radiation at wavelengths in a range of about 0.7 microns to about 1 micron. The third layer can in turn exhibit a significant absorption of solar radiation at wavelengths greater than about 1 micron.
摘要:
Photovoltaic devices (e.g., solar cells) are disclosed that include at least three radiation absorbing layers, each capable of absorbing radiation over a different wavelength range of the solar radiation spectrum. Any two of these three wavelength ranges can be partially overlapping, or alternatively they can be distinct. The layers are disposed relative to one another so as to form two junctions, each of which includes a depletion region. In some cases, the radiation absorbing layers can collectively absorb radiation over a wavelength range that spans at least about 60%, or 70%, or 80%, and preferably 90% of the solar radiation wavelength spectrum. By way of example, in some embodiments, one layer can exhibit significant absorption of solar radiation (e.g., it can absorb at least one radiation wavelength at an absorptance greater than about 90%) at wavelengths less than about 0.7 microns while another layer can exhibit significant absorption of the solar radiation at wavelengths in a range of about 0.7 microns to about 1 micron. The third layer can in turn exhibit a significant absorption of solar radiation at wavelengths greater than about 1 micron.
摘要:
Methods and apparatus for processing a substrate (e.g., a semiconductor substrate) is disclosed that includes irradiating at least a portion of the substrate surface with a plurality of short radiation pulses while the surface portion is exposed to a dopant compound. The pulses are selected to have a fluence at the substrate surface that is greater than a melting fluence threshold (a minimum fluence needed for the radiation pulse to cause substrate melting) and less than an ablation fluence threshold (a minimum fluence needed for the radiation pulse to cause substrate ablation). In this manner a quantity of the dopant can be incorporated into the substrate while ensuring that the roughness of the substrate's surface is significantly less than the wavelength of the applied radiation pulses.
摘要:
Methods and apparatus for processing a substrate (e.g., a semiconductor substrate) is disclosed that includes irradiating at least a portion of the substrate surface with a plurality of short radiation pulses while the surface portion is exposed to a dopant compound. The pulses are selected to have a fluence at the substrate surface that is greater than a melting fluence threshold (a minimum fluence needed for the radiation pulse to cause substrate melting) and less than an ablation fluence threshold (a minimum fluence needed for the radiation pulse to cause substrate ablation). In this manner a quantity of the dopant can be incorporated into the substrate while ensuring that the roughness of the substrate's surface is significantly less than the wavelength of the plied radiation pulses.
摘要:
Representative embodiments of a method for grouping participants in an activity include the steps of: (i) defining a grouping policy; (ii) storing, in a database, participant records that include a participant identifier, a characteristic associated with the participant, and/or an identifier for a participant's handheld device; (iii) defining groupings based on the policy and characteristics of the participants relating to the policy and to the activity; and (iv) communicating the groupings to the handheld devices to establish the groups.
摘要:
Textual responses to open-ended (i.e., free-response) items provided by participants (e.g., by means of mobile wireless devices) are automatically classified, enabling an instructor to assess the responses in a convenient, organized fashion and adjust instruction accordingly.
摘要:
The invention provides methods and systems for separating particles that exhibit different Raman characteristics. The method can include introducing nanoparticles, on which Raman-active molecules are adsorbed, into a photopolymerizable resin and exposing to excite Raman active vibrational modes of the molecules to generate Raman-shifted radiation suitable for polymerizing the resin such that the Raman-shifted radiation causes selective polymerization of a resin surrounding nanoparticles if the nanoparticles provide a Raman enhancement factor greater than a threshold. In addition, methods for electrically isolating nanoparticles, or selectively removing one type of nanoparticles from collections, are disclosed. These methods rely on generation of blue-shifted anti-Stokes photons to selectively expose portions of a photoresist covering the nanoparticles to those photons. Such exposure can cause a change in the exposed portions (e.g., polymerize or increase solubility to a developing agent), which can be employed to achieve isolation of the nanoparticles or their selective removal.
摘要:
In one aspect, the present invention provides a method of processing a substrate, e.g., a semiconductor substrate, by irradiating a surface of the substrate (or at least a portion of the surface) with a first set of polarized short laser pulses while exposing the surface to a fluid to generate a plurality of structures on the surface, e.g., within a top layer of the surface. Subsequently, the structured surface can be irradiated with another set of polarized short laser pulses having a different polarization than that of the initial set while exposing the structured surface to a fluid, e.g., the same fluid initially utilized to form the structured surface or a different fluid. In many embodiments, the second set of polarized laser pulses cause the surface structures formed by the first set to break up into smaller-sized structures, e.g., nano-sized features such as nano-sized rods.
摘要:
In one aspect, the present invention provides a method of processing a substrate, e.g., a semiconductor substrate, by irradiating a surface of the substrate (or at least a portion of the surface) with a first set of polarized short laser pulses while exposing the surface to a fluid to generate a plurality of structures on the surface, e.g., within a top layer of the surface. Subsequently, the structured surface can be irradiated with another set of polarized short laser pulses having a different polarization than that of the initial set while exposing the structured surface to a fluid, e.g., the same fluid initially utilized to form the structured surface or a different fluid. In many embodiments, the second set of polarized laser pulses cause the surface structures formed by the first set to break up into smaller-sized structures, e.g., nano-sized features such as nano-sized rods.
摘要:
The present invention generally provides semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.