Temperature dependence of photoluminescence from P‐doped ZnMgTe bulk crystals of high quality grown by Bridgman method

Abstract

High quality P‐doped Zn1‐xMgx Te crystals with Mg composition x of 0.09 to 0.3 were grown by vertical Bridgman method. The typical value of the full width at half maximum of (004) X‐ray ricking curve was 65.7 arcsec. For the first time temperature dependence of photoluminescence measurement were successfully attained by using the P‐doped Zn1‐xMgx Te crystals. All the crystals showed not only excitonic emission with no donor‐acceptor pair emission at low temperature but also photoluminescence (PL) band originated from interband transition at room temperature. From the temperature dependent PL intensity of free‐to‐bound (FB) transition emission, the relationship between x and the energy of P acceptor level was estimated by the use of one‐step model of thermal quenching mechanism. The result showed that the acceptor level monotonically increases with increasing x. This relationship seems to be reasonable which was supported by comparison with the energy difference between the peak of FB emission and estimated band gap at 4.2 K. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Temperature dependence of electrical properties for P-doped ZnMgTe bulk crystals of high quality grown by Bridgman method

“…It is found that resistivity tends to increase as Mg content increases while the carrier concentration tends to decrease. Such a decrease in carrier concentration may be partially due to an increase in the activation energy of P-acceptor by widening the band-gap with Mg content, which has also been revealed by the previous PL analyses [9].…”

“…The growth was carried out in almost the same manner as in the previous studies [2,8,9]. Briefly, Zn, Mg, Te and Zn 3 P 2 were used as source materials.…”

“…However, there are only a few works on phosphorus (P)-doped Zn 1 À x Mg x Te bulk crystals [4,6] except for our previous studies [2,8,9]. The incorporation of P reduces the room-temperature (RT) resistivity of p-type crystals [2,4,6], and also enhances the bandedge emission in Zn 1 À x Mg x Te [9] as well as in ZnTe [10]. Using P-doped Zn 1 À x Mg x Te bulk crystals as substrates, we have already demonstrated a green ZnTe-based LED by means of thermal diffusion process of Al [11].…”

“…With respect to bulk growth of Zn 1 À x Mg x Te crystals, several investigations have so far been carried out mainly using the Bridgman technique [1,2,[4][5][6][7][8][9], which is simple and leads to low cost. However, there are only a few works on phosphorus (P)-doped Zn 1 À x Mg x Te bulk crystals [4,6] except for our previous studies [2,8,9].…”

“…In the previous studies [2,8,9], single crystalline wafers cut from Bridgman-grown ingots have been evaluated by photoluminescence (PL) and X-ray rocking curve (XRC) measurements in addition to the characterization of lattice constant, transmissivity and Te precipitates, which also provide an important basis for serving as substrates for epitaxial growth to realize ZnTe-based LEDs with high performance. The P-doped Zn 1 À x Mg x Te bulk crystal shows a low-temperature PL spectrum consisting of bound excitonic emission due to neutral P-acceptor, P-acceptor-related freeto-bound transition emission and RT emission band originated from interband transition as mentioned above.…”