Harvard College

Gottfried Wilhelm Leibniz Universitat Hannover

Eric Mazur

Gary King

Brian Lukoff

Mengyan Shen

James Edward Carey, Iii

James Edward Carey

Rafael R Gattass

Eric Diebold

Christopher Courtney Evans

Orad Reshef

Kelly Miller

Michael G Moebius

Michael J Aziz

David E Pastor

Mark T Winkler

Sarah E Griesse-Nascimento

Limin Tong

Marko Loncar

Steven M Ebstein

Marinna Madrid

Marinus Huber

Alexander Heisterkamp

Brian R Tull

Catherine H Crouch

Daryl Vulis

Claudia Wu

Benjamin Franta

Valeria Nuzzo

Jonathan B Ashcom

Philip Alejandro Munoz

Rebecca Jane Younkin

Nabiha Saklayen

Geoffry T Svacha

Katherine C F Phillips

Hemant Gandhi

Yang Li

Chris Schaffer

Shota Kita

André Brodeur

Mark Winkler

James Edward Iii Carey

Participatory activity carried out using electronic devices is enhanced by occupying the attention of participants who complete a task before a set completion time. For example, a request or question having an expected response time less than the remaining answer time may be provided to early-finishing participants.

Management of off-task time in a participatory environment

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.

Cluster analysis of participant responses for test generation or teaching

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.

Participant grouping for enhanced interactive experience

In one aspect, a method of cell processing is disclosed, which includes disposing a plurality of cells on a substrate across which a plurality of projections are distributed and an electrically conductive layer at least partially coating said projections, exposing the cells to a cargo to be internalized by the cells, irradiating the substrate surface (and in particular the projections) with continuous wave or pulsed laser radiation. For example, one or more laser pulses having a pulse width in a range of about 1 ns to about 1000 ns can be applied so as to facilitate uptake of the cargo by at least a portion of the cells (e.g., the cells positioned in the vicinity of the projections (e.g., within hundreds of nanometer (such as less than 100 nm) of the projections)). In some embodiments, the laser pulses have a pulse width in a range of about 10 ns to about 500 ns, e.g., in a range of about 5 ns to about 50 ns.

Cellular poration using laser radiation

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.

Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

In various embodiments, subject matter for improving discussions in connection with an educational resource is identified and summarized by analyzing annotations made by students assigned to a discussion group to identify high-quality annotations likely to generate responses and stimulate discussion threads, identifying clusters of high-quality annotations relating to the same portion or related portions of the educational resource, extracting and summarizing text from the annotations, and combining, in an electronically represented document, the extracted and summarized text and (i) at least some of the annotations and the portion or portions of the educational resource or (ii) clickable links thereto.

Instructional support platform for interactive learning environments

In one aspect a method of fabricating an n-doped strained germanium (Ge) film is disclosed, which includes depositing a strained Ge film on an underlying substrate, implanting at least one electron-donating dopant in the Ge film, and exposing the implanted Ge film to one or more laser pulses having a pulsewidth in a range of about 1 ns to about 100 ms so as to generate a substantially crystalline strained Ge film. In some embodiments, the pulses can cause melting followed by substantial recrystallization of at least a portion of the implanted Ge film. In some embodiments, the resultant Ge film can have a thickness in a range of about 10 nm to about 1 microns.

N-type doping of strained epitaxial germanium films through co-implantation and nanosecond pulsed laser melting

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

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.

In one aspect, a composition of matter is disclosed, which comprises a photonic crystal comprising a plurality of 2D or 3D periodically repeating structures, where the structures are configured and arranged relative to one another such that the photonic crystal exhibits a Dirac cone at the center of the Brillouin zone of its reciprocal lattice, e.g., at one frequency in the optical regime. In some embodiments, the structures are formed of a dielectric material. In another aspect, a photonic structure is disclosed, which comprises a substrate, a plurality of periodically repeating cavities formed in said substrate, where the cavities are sized and arranged relative to one another such that said photonic structure exhibits a substantially vanishing refractive index (preferably a zero refractive index) for at least one wavelength of electromagnetic radiation propagating through said photonic structure, for example, for at least one wavelength of the electromagnetic radiation in a range of about 400 nm to about 100 microns.

Integrated impedance-matched photonic zero-index metamaterials

In various embodiments, online discussions in connection with an educational resource are improved by analyzing annotations made by students assigned to a discussion group to identify high-quality annotations likely to generate responses and stimulate discussion threads and by making the identified annotations visible to students not assigned to the discussion group.

Stimulating online discussion in interactive learning environments

In one aspect, a method of processing a semiconductor substrate is disclosed, which comprises incorporating at least one dopant in a semiconductor substrate so as to generate a doped polyphase surface layer on a light-trapping surface, and optically annealing the surface layer via exposure to a plurality of laser pulses having a pulsewidth in a range of about 1 nanosecond to about 50 nanoseconds so as to enhance crystallinity of said doped surface layer while maintaining high above-bandgap, and in many embodiments sub-bandgap optical absorptance.

Creation of hyperdoped semiconductors with concurrent high crystallinity and high sub-bandgap absorptance using nanosecond laser annealing

Growing community of inventors

Concord, MA, United States of America

Eric Mazur