The band gap energy of semiconductors tends to decrease with increasing temperature. When temperature increases, the amplitude of atomic vibrations increase, leading to larger interatomic spacing. The interaction between the lattice phonons and the free electrons and holes will also affect the band gap a little. The relationship between band gap energy and temperature can be described by Varshni's empirical expression,
In a regular semiconductor crystal, the band gap is fixed owing to continuous energy states. In a quantum dot crystal, the band gap is size dependent and can be altered to produce a range of energies between the valence band and conduction band. It is also known as quantum confinement effect.
Band gaps also depend on pressure. Band gaps can be either direct or indirect, depending on the electronic band structure.
Classically, the ratio of probabilities that two states with an energy difference "ΔE" will be occupied by an electron is given by the Boltzmann factor:
where:
At the Fermi level (or chemical potential), the probability of a state being occupied is ½. If the Fermi level is in the middle of a band gap of 1 eV, this probability is "e" or about 2.0⋅10 at the room-temperature thermal energy of 25.9 meV.
Electrons can be excited by light as well as by heat. The band gap determines what portion of the solar spectrum a photovoltaic cell absorbs. A luminescent solar converter uses a luminescent medium to downconvert photons with energies above the band gap to photon energies closer to the band gap of the semiconductor comprising the solar cell.
In photonics band gaps or stop bands are ranges of photon frequencies where, if tunneling effects are neglected, no photons can be transmitted through a material. A material exhibiting this behaviour is called a "photonic crystal".
Similar physics applies to phonons in a phononic crystal.
Deal or No Deal (UK game show)
Deal or No Deal is the British version of the game show franchise of the same name. It is presented by Noel Edmonds, and produced by Endemol. It began showing in 2005. Players can win £250,000 (US$388,800). The odds of winning it is only 4 in 1715 (1 in 429, or 2 in 858). This is because a player might take a offer from the banker.
The show is on Channel 4 at 4p.m. on weekdays. It runs for 60 minutes, including adverts.
Before the game starts, different amounts of money are packed randomly into 22 suitcases. A player is selected, and the case that they have is randomly selected.
In front of the player is a game board with all the possible amounts that could be in his/her box. The player then opens 5 boxes. Five possible amounts that could be in the player's box are gone. Based on the amounts left (that could be in the players box), the "banker" may make an offer to buy the box from the player. The offer depends on the possible amounts that could be in the player's box according to what is left on the board. So if there are high amounts that are on the board (that could be in the person's box), the banker will pay more to buy the box. He might offer £10,000 instead of £3,500 or £1500. The player may take the offer by saying "deal" of refuse it by saying "no deal".
The player then opens 3 more boxes, and the banker will make another offer. If after 6 offers, the player says "no deal", they win whatever is in their box. If they says "deal" at an offer, the player takes home the offer. The game ends, but they play on to see what would have happened otherwise.
Moves Like Jagger
"Moves Like Jagger" is a dance pop single released by American pop rock band Maroon 5 on June 22, 2011 internationally and digitally. The single features pop singer-songwriter Christina Aguilera and was produced by Shellback, Benny Blanco, and Ari Levine. The song was later put on the Maroon 5 album "Hands All Over" in July of 2011 for the re-release. The song peaked at number-one on the Billboard Hot 100 singles' chart for four weeks and number-one on the Billboard Digital Songs chart for three weeks. The song will not feature on the upcoming fourth studio album "Overexposed", which is scheduled for release on June 26, 2012.
The song's lyrics refer to a male protagonist's ability to impress a female with his dance moves, which he compares to those of The Rolling Stones frontman Mick Jagger. The song received a positive critical appreciation, many of them complimented the vocal chemistry between Levine and Aguilera and labeled it "an irresistible summer hit".
The music video for "Moves Like Jagger" was directed by Jonas Åkerlund and filmed in Los Angeles, California on July 8, 2011. On July 9, Aguilera posted an image of herself from the video shoot via Twitter, saying, "Always great to see Jonas Akerlund. He created the perfect feel for the song. Expect a fun video." The image showed Aguilera performing with a band in front of a background of the American flag. Four shirtless images of Levine from the shoot were also released online the same day. More images from the video shoot were released online on July 11, showing Levine and Aguilera performing in front of an American and British-themed backdrop with confetti falling from the ceiling. Another image showed Aguilera performing in front of a black backdrop with her name "Christina" shown in pink. Rolling Stones frontman Mick Jagger made an appearance in the video "via archive footage." The music video premiered on August 8 on E!
David Walliams
David Edward Williams (born 20 August 1971), known professionally as David Walliams, is a British actor, comedian and writer. He is known for his partnership with Matt Lucas on the TV sketch show "Little Britain" and its predecessor "Rock Profile". More recently, he and Lucas wrote and starred in "Come Fly with Me".
Born in Wimbledon, London on 20 August 1971 to Peter, a London Transport engineer, and Kathleen Williams, a lab technician, Williams was brought up in Banstead. His parents appeared on "The Friday Night Project" when he was the guest star on the show.
He was educated at Collingwood Boys' School in Wallington (now Collingwood School) and the independent Reigate Grammar School (where he was a contemporary of Robert Shearman).
He was a member of the National Youth Theatre, where he met Matt Lucas. Williams studied drama at the University of Bristol from 1989 to 1992, one year below Simon Pegg.
Williams changed his name to Walliams () when he joined the actors' trade union, Equity, as there was already a member named David Williams. This was spoofed in a mock interview on "Rock Profile", when Robbie Williams was continuously referred to as 'Robbie Walliams'.
David Walliams was also a judge for BGT(Britain's Got Talent). In September 2011, he swam the entire 140 mile length of the River Thames, raising over £1,000,000 for a charity called Sport Relief.
Walliams has bipolar disorder. He was married to Lara Stone from 2010 until their divorce in 2015. They have a son, Alfred Walliams.
Luton
Luton is a large town in Bedfordshire, England. It is about north of London. It is on the M1 motorway and has mainline trains from King's Cross and St Pancras stations. It is an industrial town which has diversified from its original base as a manufacturer of hats and cars. Its fine communications means it has many people who commute to work in London. It has a population of 213,052 (mid-2019 estimate).
Luton was started in about the 6th century by the Saxons, based by the River Lea. It has a history of industry: making hats and Vauxhall cars for example.
Luton is a unitary authority, which means it is governed locally by its own council, Luton Borough Council. It is represented by two members of parliament.
Its football club is in the English football league and play at Kenilworth Road. Their nickname is 'The Hatters'. They are called this because of Luton's history of making straw hats.
Luton town has a large immigrant population, which consists mainly of people of Pakistani and Bengali origin.
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