Investigation of spectral and energy characteristics of green radiation generated in lithium fluoride with radiation color centers

Abstract

A new metal-oxide-silicon (MOS)/bipolar merged transistor structure in a silicon on insulator (SOI), which has a MOS structure with a built-in bipolar mechanism, is proposed. The transistor has a frame of a metal-oxide-silicon field-effecttransistor (MOSFET) having the gate at the bottom. A vertical bipolar transistor is built in the drain region by introducing an opposite-type impurity through a polycrystalline silicon buffer layer. Implementation of the device in an SOI structure avoids parasitic effects such as the latch-up, which appears when a merged structure is used to construct a complementary circuit. A two-dimensional device simulation shows the current amplification property of the merged transistor, while also revealing the critical design parameter for successful operation. A test device is fabricated using a process which employs a wafer bonding and polish-back technique. The results prove the feasibility of the proposed device.

Thermoluminescence of pure LiF crystals and color centers

“…Of the crystals colored at À60 1C, one was used as such (sample C), while the other was illuminated at RT for about 1 h with the 308 nm line of a XeCl excimer laser (sample D). Irradiation of LiF by g-rays, or by any other ionizing radiation, produces absorption bands in the spectral region from 200 to 1000 nm, due in the order of increasing wavelength and usually decreasing absorption intensity to F, F 3 , F 2 , F 3 + , F 4 , F 2 + , F 3 À , and F 2 À CCs [5][6][7][8]. In the present case, the irradiation with g-rays was not very intense, and so F 3 À and F 2 À centers were not detected, while F 2 + centers are not stable at RT.…”

Permanent bleaching of F2 color centers in lithium fluoride under UV light illumination

“…A transition of a color center to these states can be accompanied by their ionisation, reorientation, or dissociation. As far as F 2 centers are concerned, permanent bleaching-annealing [11] has been obtained by powerful laser shots at 308 nm. The presence of the F absorption band at 244 nm makes an investigation of spectral position of highly excited states difficult.…”

Aggregate color center formation processes in lithium fluoride crystals after irradiation

“…This means that during the entire time while the D 1 (t) dependences were recorded, the F 2 centers were being ionized and electrons were appearing which then could combine with vacancies and generate F 1 centers. This reaction was neglected when formulating relations (20) and (21). Thus in the time range corresponding to the fast initial stage of the D 1 (t) dependence, two reactions occur, i.e., we can say that the nature of formation of this stage is complicated.…”

“…The absence of electrons rules out participation in the aggregation for reaction (6) (which results in generation of F 2 centers) and the reaction F 3 + + e → F 3 (which leads to a decrease in the number of F 3 + centers). All these facts are used in designing an active medium for achieving lasing based on F 3 + centers [21].…”