Field effect transistor diamond

Philippe Bergonzo and Richard B. Jackman, Diamond-Based Radiation and Photon Detectors Hiroshi Kawarada, Diamond Field Effect Transistors Using H-Terminated Surfaces Shinichi Shikata and Hideald Nakahata, Diamond Surface Acoustic Wave Device... 

Chemical vapor deposition films have been grown on an Ir/SrTiOs substrate of around 0.6 cm for a field effect transistor application achieving for the first time an RF output power for a device operating at frequencies of the order 10 Hz. Larger-size substrates will eventually allow the development of power diamond transistors at wafer scale. ... 

Kubovic, M. Aleksov, A. Schreck, M. Bauer, Th. Stritzker, B. Kohn, E. Field effect transistor fabricated on hydrogen-terminated diamond grown on SrTiOs substrate and iridium buffer layer. Diamond Relat. Mater. 2003, 12, 403-407. 

Preliminary developments of semiconductor devices based on CVD diamond are already under way including field-effect transistors (FET) which are proving superiorto silicon devices and are characterized by high-power handling capacity, low saturation resistance, and excellent high-frequency performance.P8]... 

Second, a diamond surface with NEA exhibits a novel doping mechanism that relies on the low ionization energy of diamond with NEA. This transfer doping mechanism yields a subsurface hole accumulation layer and a concomitant high surface conductivity (SC) that is discussed in volume 6. Field effect transistors (FETs) based on this kind of SC have been built [33-35], and attempts are being made to exploit the sensitivity of SC in diamond for ion-sensitive electronic devices such as ion-sensitive FETs (ISFETs) [36, 37]. 

Landstrass and Ravi first reported the p type surface conductivity of diamond [80, 81]. Gi et al. [82, 83] showed that the surface conductivity increased when exposed to acidic vapors and decreased when exposed to basic vapors. This near-surface p type conductivity is characterized by a high carrier sheet density of about 10 cm 2 from 150 400 K, an activation energy of less than 50 meV, and a low density of surface states [78, 84-86]. These attributes have led to its application in electronic devices such as field effect transistors [84-86]. 

Apart from transistors, several other solid state devices have been discussed [78], like junctions, photon and electron beam switches and various kinds of sensors. One property of diamond which has stimulated considerable interest in the recent years is the negative electron affinity (NEA) of suitably prepared surfaces [78,80]. The electron affinity, of a material is defined as the difference between the energy of a free electron in vacuum and the bottom of the conduction band Fyac - E. In Fig. 8 the electronic bands of p-doped clean and H-terminated (111) diamond surfaces near the surface are depicted, based on the results of UV-photoemission measurements. For the H-terminated surface, the electron affinity becomes negative once an electron is injected into the conduction band from a suitable contact or by UV excitation, it will easily leave the crystal and be emitted into vacuum. This effect, which is also observed on monohydride terminated (100) surfaces, is not unique to diamond but was also observed in a few other semieonductors with high band gaps [80]. Apart from a scientific interest, the NEA of diamond makes it an attractive eandidate for the replacement of thermionic emitters as electron beam sourees and as a miniature electron emitter for field emission displays. 

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