Journal of Crystal Growth 301–302 (2007) 252–255 Observation of abrupt first-order metal–insulator transition in Be-doped GaAs Hyun-Tak Kim a,Ã , Doo-Hyeb Youn a , Byung-Gyu Chae a , Kwang-Yong Kang a , Yong-Sik Lim b a Telecommunications Basic Research Laboratory, ETRI, Daejeon 305-350, Republic of Korea b Department of Applied Physics, Konkuk University, Chungju, Chungbuk 380-701, Republic of Korea Available online 17 January 2007 Abstract An abrupt first-order metal–insulator transition (MIT) as a current jump is observed in Be-doped GaAs by inducing holes in a very low concentration of n p  5  10 14 cm 3 into the valence band by the electric field; this is anomalous. In a higher hole-doping concentration of n p  6  10 16 cm 3 , the abrupt MIT is not observed at room temperature, but measured at a low temperature. The upper limit of the temperature allowing the MIT is deduced from experimental data to be approximately 440 K. The abrupt MIT is intrinsic and is compared with ‘‘breakdown’’ (an unsolved problem) produced by a high electric field in semiconductor devices. r 2006 Elsevier B.V. All rights reserved. PACS: 71.27.þa; 71.30.þh Keywords: A1. Avalanche breakdown; A1. First-order metal–insulator transition; A1. Molecular beam epitaxy; B1. GaAs; B3. Devices Since Mott predicted the abrupt first-order metal–insu- lator transition (MIT) not accompanied with a structural phase transition [1], the abrupt Mott MIT as a current jump was first proved experimentally in VO 2 [2,3]. For a representative application of the MIT, the current jump provides a nano-level heat source for melting of a material for development of the next generation non-volatile memory [4]. The jump has been actually observed in insulators, CeO 2 [4], CaCu 3 Ti 4 O 12 [5], yðBEDTTTFÞ 2 CsZnðSCNÞ 4 [6], GaAs [7–12]. Besides these, many materials showed the current jump. Kim et al. predicted that the abrupt MIT would occur even in some p-type semiconductors having an energy gap less than 2 eV as well as Mott insulators [2]. For GaAs, p-typed films with lower hole-doping concentrations exhibited a thermally activated semiconduction, while those films with higher doping concentrations showed the metallic conduction at room temperature [13]. This revealed a continuous MIT with increasing hole-doping concentration. Moreover, in an optically excited semicon- ductor InGaAs/GaAs quantum well, an excitonic MIT occurs gradually with increasing carrier concentration; the researchers suggested that this is an evidence of the Mott transition in semiconductors [14]. However, in accordance with the prediction of the presence of the abrupt MIT [2], we have investigated the occurrence of the current jump as the first-order MIT in GaAs. In this paper, we demonstrate an abrupt first-order MIT, a continuous MIT, and the temperature dependence of the abrupt MIT, by inducing hole charges in hole levels into the valence band using an electric field in Be-doped GaAs- based two-terminal devices. The concept for this research comes from the hole-driven MIT theory (extended Brink- man–Rice picture) [2,15,16]. Furthermore, the breakdown phenomenon with filamentary conduction in semiconductor physics [12] is discussed in light of the abrupt MIT. Be-doped p-type GaAs films were deposited on (1 0 0) GaAs substrates by molecular beam epitaxy. To fabricate two-terminal devices (inset of Fig. 1(a)), most of the p-type GaAs film except a very small patch ð100  100 mm 2 Þ patterned by a mask was removed by an Ar beam. This ARTICLE IN PRESS www.elsevier.com/locate/jcrysgro 0022-0248/$ - see front matter r 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2006.11.199 Ã Corresponding author. E-mail address: htkim@etri.re.kr (H.-T. Kim).